Support ImGui 1.91.5 and greater

[jslee02]

• Updated the special key mapping between OSG and ImGui as per New IO keyboard/mouse/gamepad event API (1.87) recap ocornut/imgui#4921 to resolve build issues caused by the removed ImGui API since version 1.91.5.
• Renamed the Pixi task from configure to config for brevity.

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Before creating a pull request

• Document new methods and classes
• Format new code files using ClangFormat by running make format
• Build with -DDART_TREAT_WARNINGS_AS_ERRORS=ON and resolve all the compile warnings

Before merging a pull request

• Set version target by selecting a milestone on the right side
• Summarize this change in CHANGELOG.md
• Add unit test(s) for this change
• Add Python bindings for new methods and classes

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 61.55%. Comparing base (1093809) to head (957b599).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1872   +/-   ##
=======================================
  Coverage   61.55%   61.55%           
=======================================
  Files         490      490           
  Lines       46013    46013           
=======================================
  Hits        28325    28325           
  Misses      17688    17688