[3.14] gh-83274: Don't crash when a Tcl interpreter is deallocated in the wrong threa...

[3.14] gh-83274: Don't crash when a Tcl interpreter is deallocated in the wrong thread (GH-152323) (GH-153277)

Deallocating the interpreter from a thread other than the one it was created
in ran Tcl_DeleteInterp() there, which makes Tcl abort the process
("Tcl_AsyncDelete: async handler deleted by the wrong thread").

Tkapp_Dealloc() now leaks the interpreter in that case and reports a
RuntimeWarning instead.

(cherry picked from commit 46d1809ccd4bc0e1439a4696b428d2a1c2edcfbf)

Co-authored-by: E. Paine <63801254+E-Paine@users.noreply.github.com>
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>