XBND-1931: pipeline fixes

• conf.py cleanup
• setting to exclude api docs for doxygen sources locally added to repo_manifest.yml
• moved _doxygen mappings inside repo manager startup lifecycle
• docker build confirmed: no longer overlaps source from build, but that means you must rebuild the sphinx image to add sources
• local venv build confirmed: now installs to xbe-venv folder specifically
• local conda build confirmed: works like a charm
• updated csharp filtering for less spam (still some to fix)
• all scripts in tools/ now use Push-Location and Pop_Location instead of caching location

TODO before merge:

• reset dev_mode branches in docs/repo_manifest.yml after merging the followng:
  • https://source.goxbe.io/Core/sdk/sdk_csharp/-/merge_requests/47
  • https://source.goxbe.io/Core/sdk/sdk_nodejs/-/merge_requests/27
  • https://source.goxbe.io/Core/sdk/sdk_unity/-/merge_requests/34
• reset sphinx_image_min branch in docs/requirements.txt after merging the following:
  • sphinx_image_min!1 (merged)

Updates XBND-1931