Add support for installing latest build from main to scripts and update docs.

[joperezr]

This should make it easier to dogfood latest nightly build by adding this support to our installLatest... scripts. This also updates the dogfooding docs in our repo.

cc: @mitchdenny

Microsoft Reviewers: Open in CodeFlow

[joperezr]

FYI @balachir since this can now change the dogfooding instructions your team uses going forward.

[eerhardt]

Script changes look good. Just a suggestion on the document.

[danmoseley]

How should I choose? Something like "The main branch will generally have the most recent code, while the release branch will generally have been more tested."

[joperezr]

In reality, nowadays you really only want -FromMain always, as the script doesn't work with stable builds, and since all of the builds out of our release branch are stable now, it means the release branches support doesn't work now. I think the way forward is that the script should be changed such that the default (without params) installs you latest build from main, and if you specify a flag we instead install you the latest GA build.

[joperezr]

I can either do that in this PR or as a follow up. Since I'll be out for two weeks and some people might benefit from this today, I tempted to push support for main now and then as a follow up fix the scripts to support the above.

[mitchdenny]

I just tried this out on a devbox and it didn't configure the templates:

Output from command:

PS C:\Code\aspire\eng> .\installLatestFromReleaseBranch.ps1 -FromMain

Advertising manifest not updated. Manifest package for microsoft.net.workload.mono.toolchain.current doesn't exist.
Advertising manifest not updated. Manifest package for microsoft.net.workload.emscripten.current doesn't exist.
Skipping NuGet package signature verification.
Updated advertising manifest microsoft.net.workload.emscripten.net6.
Updated advertising manifest microsoft.net.sdk.android.
Updated advertising manifest microsoft.net.workload.emscripten.net7.
Updated advertising manifest microsoft.net.workload.mono.toolchain.net7.
Updated advertising manifest microsoft.net.workload.mono.toolchain.net6.
Updated advertising manifest microsoft.net.sdk.maui.
Updated advertising manifest microsoft.net.sdk.ios.
Updated advertising manifest microsoft.net.sdk.macos.
Updated advertising manifest microsoft.net.sdk.tvos.
Updated advertising manifest microsoft.net.sdk.aspire.
Updated advertising manifest microsoft.net.sdk.maccatalyst.
The machine has a pending reboot. The workload operation will continue, but you may need to restart.
Downloading microsoft.net.sdk.aspire.manifest-8.0.100.msi.x64 (8.1.0-preview.1.24326.3)
Installing microsoft.net.sdk.aspire.manifest-8.0.100.msi.x64 ...... Done
Downloading Microsoft.Android.Sdk.Windows.Msi.x64 (33.0.95)
Workload installation failed. Rolling back installed packs...
Removing microsoft.net.sdk.aspire.manifest-8.0.100.msi.x64 .... Done
Workload update failed: One or more errors occurred. (Version 33.0.95 of package microsoft.android.sdk.windows.msi.x64 is not found in NuGet feeds https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet8/nuget/v3/index.json".)

Workload(s) 'aspire' are already installed.
Advertising manifest not updated. Manifest package for microsoft.net.workload.mono.toolchain.current doesn't exist.
Advertising manifest not updated. Manifest package for microsoft.net.workload.emscripten.current doesn't exist.
Skipping NuGet package signature verification.
The machine has a pending reboot. The workload operation will continue, but you may need to restart.
Downloading Aspire.Hosting.Sdk.Msi.x64 (8.1.0-preview.1.24326.3)
Installing Aspire.Hosting.Sdk.Msi.x64 .... Done
Downloading Aspire.ProjectTemplates.Msi.x64 (8.1.0-preview.1.24326.3)
Installing Aspire.ProjectTemplates.Msi.x64 .... Done
Downloading Aspire.Hosting.Orchestration.win-x64.Msi.x64 (8.1.0-preview.1.24326.3)
Installing Aspire.Hosting.Orchestration.win-x64.Msi.x64 ...... Done
Downloading Aspire.Hosting.Msi.x64 (8.1.0-preview.1.24326.3)
Installing Aspire.Hosting.Msi.x64 .... Done
Downloading Aspire.Dashboard.Sdk.win-x64.Msi.x64 (8.1.0-preview.1.24326.3)
Installing Aspire.Dashboard.Sdk.win-x64.Msi.x64 ..... Done
Downloading Microsoft.Android.Sdk.Windows.Msi.x64 (33.0.95)
Workload installation failed. Rolling back installed packs...
Removing Aspire.Dashboard.Sdk.win-x64.Msi.x64 ..... Done
Removing Aspire.Hosting.Msi.x64 .... Done
Removing Aspire.Hosting.Orchestration.win-x64.Msi.x64 .... Done
Removing Aspire.ProjectTemplates.Msi.x64 .... Done
Removing Aspire.Hosting.Sdk.Msi.x64 .... Done
Removing microsoft.net.sdk.aspire.manifest-8.0.100.msi.x64 .... Done
Workload installation failed: One or more errors occurred. (Version 33.0.95 of package microsoft.android.sdk.windows.msi.x64 is not found in NuGet feeds https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet8/nuget/v3/index.json".)
Installed Latest version of .NET Aspire produced from the main branch. Version installed was 8.1.0-preview.1.24326.3.

Then I jumped up to a clean parent directory and executed this command to create a starter project:

$ dotnet new aspire -o Dogfood81
No templates or subcommands found matching: 'aspire'.

To list installed templates similar to 'aspire', run:
   dotnet new list aspire
To search for the templates on NuGet.org, run:
   dotnet new search aspire


For details on the exit code, refer to https://aka.ms/templating-exit-codes#103

[joperezr]

I just tried this out on a devbox and it didn't configure the templates

I followed up with @mitchdenny offline about this and he is now in a working state. The issue he was hitting was that he was using an 8.0.400 preview SDK which depended on unreleased packages for other workloads. This was fixed by adding the dotnet7 feed to his sources.

[joperezr]

Forgot to merge this PR. Merging as I just validated and scripts still work as expected and it would be good for folks to dogfood.