upgrade to gdunit v6

[bitbrain]

Note

Upgrade to GdUnit4 v6 and refactor runners, reporters, networking, UI, and tooling, adding .NET support and improved parsing/mocking.

• GdUnit Upgrade & Core:
  • Upgrade to GdUnit4 (v6) with new session-based runners (GdUnitTestSessionRunner, GdUnitTestRunner, GdUnitTestCIRunner).
  • Introduce unified reporters (console, html, xml) via GdUnitReportWriter and replace legacy report classes.
  • Overhaul message writers (rich-text/CSI) and TCP layer (GdUnitTcpNode, client/server protocol, RPC serialization).
  • Add .NET/C# API bridge and loader, removing old mono bridge.
  • Refactor mocking/spying with function doubler builder; simplify CallableDoubler varargs.
  • Enhance GDScript parser: regex tokens, variadics, argument enrichment, return type handling.
• UI/Inspector:
  • Revamp test inspector: flat/tree restructuring, live counters (success/failed/flaky/skipped), progress events, improved status icons.
  • Console output rewritten using GdUnitConsoleTestReporter; fonts/colors aligned with editor.
• Reporting & Hooks:
  • HTML patterns tweaked; new path/suite pages; add hooks settings tab; hook management UI.
• Update/Patching:
  • Update flow can patch invalid UIDs, reimport resources, and rebuild .NET projects.
• Project/Tests:
  • Bump project to Godot 4.5; adjust texture import params.
  • Minor API rename in tests (set_mouse_position).