Use UID for the assets folder and manifest

[isaacroldan]

WHY are these changes introduced?

Fixes the inconsistency in how extension assets are referenced in the bundling process.

WHAT is this pull request doing?

This PR changes how extension assets are referenced during the bundling process:

1. Updates manifest generation to use the more explicit module.outputFolderId instead of module.uid for assets folder.
2. Adds a new outputFolderId getter to the ExtensionInstance class that returns the extension's uid
3. Refactors the keepBuiltSourcemapsLocally, buildForBundle, and copyIntoBundle methods to use the extension's outputFolderId directly
4. Removes the now-redundant getOutputFolderId method and simplifies related code

How to test your changes?

1. Create an app with multiple extensions
2. Run shopify app deploy to verify extensions are deployed correctly
3. Verify that sourcemaps are correctly preserved in the extension folder
4. Try to deploy a recently migrated app: everything should work

Measuring impact

How do we know this change was effective? Please choose one:

• n/a - this doesn't need measurement, e.g. a linting rule or a bug-fix

Checklist

• I've considered possible cross-platform impacts (Mac, Linux, Windows)
• I've considered possible documentation changes

[isaacroldan]

• Use UID for the assets folder and manifest #6183 👈 (View in Graphite)
• main

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[github-actions]

Coverage report

St.❔	Category	Percentage	Covered / Total
🟡	Statements	78.25% (+0% 🔼)	13140/16792
🟡	Branches	72.29% (+0.03% 🔼)	6396/8848
🟡	Functions	78.36%	3407/4348
🟡	Lines	78.63% (+0% 🔼)	12437/15818

Show files with reduced coverage 🔻

St.❔	File	Statements	Branches	Functions	Lines
🟢	... / extension-instance.ts	82.11% (-0.19% 🔻)	75.91% (-0.52% 🔻)	92.86%	81.82% (-0.2% 🔻)
🟢	... / theme-command.ts	79.22% (-1.86% 🔻)	51.35% (-0.08% 🔻)	76.47%	80.82% (-2.04% 🔻)

Test suite run success

3103 tests passing in 1322 suites.

Report generated by 🧪jest coverage report action from 8d49cb1

[github-actions]

We detected some changes at packages/*/src and there are no updates in the .changeset.
If the changes are user-facing, run pnpm changeset add to track your changes and include them in the next release CHANGELOG.

Caution

DO NOT create changesets for features which you do not wish to be included in the public changelog of the next CLI release.

[alexanderMontague]

/snapit

[alfonso-noriega]

/snapit