feat(workspace-tree): Sync open editor with workspace tree view

[cbandera]

This PR implements a synchronization between the file opened in the editor and the workspace tree view of the bazel extension.

Note on implementation:
The implementation of reveal() in the tree view required proper parent-child relationships and package path resolution. The changes ensure that:

1. The tree view can properly navigate and reveal items by maintaining correct parent references
2. Package paths are consistently resolved through the parent chain
3. The selected item in the tree view is synchronized with the currently open editor

A cache of BazelPackageTreeItems was added to improve performance by:

• Reducing redundant package path calculations
• Avoiding bazel queries performed by existing getChildren operator
• Minimizing repeated string operations when resolving package paths

This PR is part of #353

[cbandera]

@cameron-martin , @vogelsgesang I assumed the tests might be failing because the github runner env doesn't have bazel installed, but adding it to the workflow file didn't solve the problem. The tests run through locally (even though I got the same error once). So they might also be flaky - I have the feeling it could have something to do with timing. Maybe we need to wait longer inside the testcase, but I am unsure how and where to do it.
Any hints on how to debug this are welcome.

Update: I solved it now by explicitly calling the asynchronous sync function and awaiting it's result. I guess that's good enough for the test, but if someone knows of a more elegant way to do this feel free to comment.
Update 2: 😝 Oh man, that only fixed it locally. I also added a step in CI to build the workspace once to assure the local bazel instance is warmed up to speed up queries within the test cases. But still no success.

[cbandera]

@cameron-martin , @vogelsgesang I have deactivated the one problematic test case for now, so that this PR becomes green anyway.
As stated before, the feature works when manually starting the extension and performing this test case, I just can't get the automated test to work, probably due to timing/concurrency issues.
If you have the time to analyze or even fix the testcase, feel free to do so. Otherwise I am also happy for any advice you can give.

[cameron-martin]

Looks like the tests are failing even though you disabled the problematic test. Could you take a look at this?

[cbandera]

@cameron-martin I had to update the test to recent changes on master. The pipeline is now successfull again.
But I am still at a loss at why the last test is not working. There must be some things screwed up with respect to global state and/or timing or concurrency. I am trying to look into this again, but as the feature is working locally, I vote for merging this PR without the automated test and try to add that in a followup.

[cbandera]

Ok found it and fixed it. The problem was that due to the way the test was setup, there were multiple instances of the treeview provider which messed things up.
I now changed it to use the one single instance of the running extension for testing. Which fixes all tests.