Move to manifest v3

[mlissner]

We're going to have to do this eventually, so this is just a place to put some notes. Here are the first two notes from me:

1. We have a label for this:

manifestv3

2. There's a boilerplate that I came across today that might be useful:

https://github.com/fstanis/webextensions-webpack-boilerplate

No idea if it's up to date, but it'd be great if it were.

[mlissner]

A few more comments:

1. Nick Sethi actually has a branch that does MV3. It might be easier to use his branch or it might be easier to go from scratch. I don't know, but we should at least evaluate it. I think he developed the extension from scratch in his branch. 😲

2. Before we do this, we should evaluate this issue: Using exportInstance and importInstance goes against convention and causes issues #237 and decide how it factors into MV3. I think we'll resolve it without trying just by doing MV3-like architecture, but let's make sure.

[mlissner]

Two developments here:

1. Google is now showing a banner warning people about RECAP. I can't seem to find it, but a few people have reported it.

2. A large gov't body just asked why we don't have RECAP in the MS Edge store, which, per Add RECAP to the MS Edge store #368, is because it's not on Manifest v3.

[mlissner]

Feedback from installing it, so far. Two things:

1. The icon is busted there. That could certainly be because of OS-level sandboxing, so if nobody else sees it, it's probably just me.
2. There's a warning still, but perhaps it's expected?

[ERosendo]

@mlissner should we close this issue? After merging freelawproject/recap-chrome#387, the extension is all set with Manifest V3.

[mlissner]

Yep!! Thank you for your hard work!