Fetch multiple resource types in ResourceContainer

[AndrewTwydell]

What It Does
Allows multiple resource types to be fetched with a single ResourceContainer, allowing multiple resources under the same parent tree. It also proportionally shares the page count between the resource types.

eg, if there were 2000 Local Files and 1000 Remote files under a single Files tree, with a page count of 300, each page would contain 200 local files and 100 remote files.

Review Checklist
I certify that I have:

• tested my changes
• added/updated automated tests
• updated the changelog
• considered whether the docs need updating
• followed the contribution guidelines

Additional Comments

[codecov-commenter]

Codecov Report

❌ Patch coverage is 81.94444% with 52 lines in your changes missing coverage. Please review.
✅ Project coverage is 69.15%. Comparing base (e94e9ec) to head (b4366fe).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
packages/vsce/src/commands/showLibraryCommand.ts	9.09%	10 Missing ⚠️
...ckages/vsce/src/commands/filterResourceCommands.ts	14.28%	6 Missing ⚠️
packages/vsce/src/trees/CICSTree.ts	50.00%	6 Missing ⚠️
...s/vsce/src/commands/inspectResourceCommandUtils.ts	33.33%	4 Missing ⚠️
packages/vsce/src/resources/ResourceContainer.ts	95.83%	4 Missing ⚠️
packages/vsce/src/utils/treeUtils.ts	60.00%	4 Missing ⚠️
packages/vsce/src/trees/CICSPlexTree.ts	81.25%	3 Missing ⚠️
packages/vsce/src/trees/CICSSessionTree.ts	57.14%	3 Missing ⚠️
...ckages/vsce/src/commands/getFilterPlexResources.ts	0.00%	2 Missing ⚠️
packages/vsce/src/commands/inquireProgram.ts	33.33%	2 Missing ⚠️
... and 6 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #455      +/-   ##
==========================================
+ Coverage   68.24%   69.15%   +0.90%     
==========================================
  Files         165      164       -1     
  Lines        3883     3932      +49     
  Branches      549      546       -3     
==========================================
+ Hits         2650     2719      +69     
+ Misses       1233     1213      -20     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.