Replace install-test-workspace with usePnpmSyncForInjectedDependencies=true

[g-chao]

Summary

Before, the install-test-worspace is a standalone pnpm workspace project inside Rushstack.
Now, we have integrated the pnpm-sync feature, so we can refactor this project to use pnpm-sync to manage injected dependencies.

Details

1. Enable usePnpmSyncForInjectedDependencies in experiments.json
2. Move the install-test-worspace folders into a new Rush category folder build-tests-subspace

👉 This PR introduces injected dependencies but not subspaces yet. The folder is named build-tests-subspace because a future PR will enable the Rush subspaces feature to reintroduce a separate lockfile for these projects.

How it was tested

• Make sure all CI checks passed in the new set up
• Confirm that the feature works with rush:
  1. Build the repo with rush build
  2. Add console.log("TEST 1") to rush-lib/src/index.ts
  3. Run incremental build: rush build --to rush-lib-test --verbose
  4. Confirm that cd rush-lib-test && node lib/start.js prints TEST 1, showing the updated files were copied successfully
• Confirm that the feature works with rushx:
  1. Add console.log("TEST 2") to rush-lib/src/index.ts
  2. cd rush-lib && rushx build
  3. Confirm that cd rush-lib-test && node lib/start.js prints TEST 2, showing the updated files were again copied successfully

Impacted documentation

N/A

[iclanton]

The new projects should have build cache configured.

[octogonz]

It can be fixed in a separate PR, but this log notice can be improved.

1. Like the build cache notices, it should only be shown when invoking rush build --verbose.

2. Also I would suggest to improve the formatting of the message:

   pnpm-sync: Copied 107 files in 95ms from C:\Git\rushstack\libraries\terminal
   

3. It seems pnpmSyncCopy() is printing this message directly to the console. We should improve the API to provide a messaging callback that allows the output to be redirected and (ideally) optionally reformatted. Something like this:

   pnpmSyncCopy({
     pnpmSyncJsonPath,
     messageCallback: ({ message, messageKind: 'error'|'warning'|'info'|'verbose'|'timing', messageId, details }) => {
       if (messageKind === 'verbose' && !debug) {
         return;
       }
       switch (messageId) {
         case 'sync-finished':
           // customized logging; the structure of details can depend on messageId
           terminal.writeLine(colors.green('pnpm-sync') 
             + ` copied ${details.fileCount} files in ${details.totalMs} ms from ${details.sourcePath}`);
           break;
         default:
           // simple preformatted logging
           if (messageKind === 'error' | messageKind === 'warning') {
             console.error(message);
           } else {
             console.log(message);
           }
           break;
       }
     }
   })

   This would ensure that Rush (and in the future PNPM) has full ownership of its CLI UX.

@g-chao @iclanton

[octogonz]

tiktok/pnpm-sync#14