feat(txtar): add loadpkg command

[gfanton]

address #1484

This PR introduces the loadpkg command to gnoland integration using txtar:

- Must be run before `gnoland start`.
- Loads a specific package from the example folder or from the working ($WORK) directory.
- Can be used to load a single package or all packages within a directory.
- If the target package has a `gno.mod`, all its dependencies (and their respective
  dependencies) will also be loaded.
- The command takes either one or two arguments. The first argument is the name of the package(s),
  and the second (optional) argument is the path to the package(s).
  Examples:
  -- # Load a package from the example packages directory:
  -- loadpkg gno.land/p/demo/ufmt
  -- # Load a package `./bar` from the current testscript's working directory with the name `gno.land/r/foobar/bar`:
  -- loadpkg gno.land/r/foobar/bar $WORK/bar
- If the path is not prefixed with the working directory, it is assumed to be relative to the
  examples directory.
- It's important to note that the load order is significant when using multiple `loadpkg`
  command; packages should be loaded in the order they are dependent upon.

Additionally, this PR disables the default automatic loading of the example folder to keep test requirements minimal.

Moreover, it remove other testX users as specified in #1484 and retaining only the test1 user. Additional users can be added as needed using the adduser command.

Contributors' checklist...

• Added new tests, or not needed, or not feasible
• Provided an example (e.g. screenshot) to aid review or the PR is self-explanatory
• Updated the official documentation or not needed
• No breaking changes were made, or a BREAKING CHANGE: xxx message was included in the description
• Added references to related issues and PRs
• Provided any useful hints for running manual tests
• Added new benchmarks to generated graphs, if any. More info here.

[codecov]

Codecov Report

Attention: Patch coverage is 54.47154% with 56 lines in your changes are missing coverage. Please review.

Project coverage is 44.56%. Comparing base (16c7c2e) to head (bca5a19).

Files	Patch %	Lines
gno.land/pkg/integration/testing_integration.go	63.80%	27 Missing and 11 partials ⚠️
gno.land/pkg/gnoland/genesis.go	0.00%	18 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1598      +/-   ##
==========================================
- Coverage   47.41%   44.56%   -2.85%     
==========================================
  Files         385      460      +75     
  Lines       61319    67903    +6584     
==========================================
+ Hits        29074    30264    +1190     
- Misses      29826    35102    +5276     
- Partials     2419     2537     +118     

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[deelawn]

Looks good to me other than the few minor comments.

[deelawn]

One more thing -- I noticed in the issue referenced here that it also says the premined addresses and balances should be removed, maybe with the exception of test1. Is that a change that should be included in this PR as well?

[gfanton]

One more thing -- I noticed in the issue referenced here that it also says the premined addresses and balances should be removed, maybe with the exception of test1. Is that a change that should be included in this PR as well?

oh, yes you right! I will remove this in this PR, as it's not needed anymore with the adduser command !

[zivkovicmilos]

Amazing 👏

No specific comments, just a typo and an observation. Looks great 💯

[harry-hov]

Just left a few suggestions that might be worth taking a look. Rest LGTM 💯

[tbruyelle]

Great addition, but why calling it use ? addpkg sounds more appropriate to me.

[moul]

Do we keep at least one oldskool gnokey maketx addpkg -pkgdir $WORK/bar -pkgpath gno.land/r/foobar/bar -gas-fee 1000000ugnot -gas-wanted 2000000 -broadcast -chainid=tendermint_test test1?

"Use" looks better, but since it's an integration test system, we need to explicitly keep at least one "using gnokey".

[thehowl]

So, @gfanton, from the review meeting:

• Let's consider whether it makes sense to change the name from use to something more descriptive. addpkg is an option, but since this is not an alias but rather adding the packages at genesis, maybe copy? (so like dockerfiles)
• • the comment about documenting usage before gnoland start

thanks!

[gfanton]

@tbruyelle @moul @thehowl I think copy would have been a good choice if packages were loaded individually. However, for practical reasons, it also loads package dependencies recursively based on the gno.mod file of the package (and sub-packages). (i've updated doc.go to mention this)
Even though it can be a bit confusing, I would say it's more accurate to use addpkg or loadpkg. Alternatively, we could simply use import, but it could be ambiguous compared to gno/go import.
wdyt ?

[thehowl]

From the review meeting: agreed on load