Improve gir build and convert build summary to meson builtin
This merge request contains a few small changes to improve the build environment:
- Improve gir build - converts the introspection option to a combo (Auto/True/False). This mimics the feature type without breaking downstream compatibility. This now properly handles missing dependencies and makes vapigen and pygobject depenendent prereqs.
- Improve cross build: set build environment tools to native.
- Convert the build summary to meson builtin - less formatting and displays the summary after any included subprojects.
- Remove unneeded dependency checks
- Code cleanup - remove some spurious whitespace
The merge request passes all CI.