[PyROOT] Implement TPython in terms of CPyCppyy API

[guitargeek]

Draft PR for now.

[github-actions[bot]]

Test Results

    13 files      13 suites   2d 18h 11m 39s :stopwatch:  3 025 tests  3 024 :white_check_mark: 0 :zzz:  1 :x: 33 806 runs  33 795 :white_check_mark: 0 :zzz: 11 :x:

For more details on these failures, see this check.

Results for commit 75ff082a.

:recycle: This comment has been updated with latest results.

[guitargeek]

Closing, because at this point it's not clear to me whether the functionality should be in TPython or in CPyCppyy.