gh-83274: Don't crash when a Tcl interpreter is deallocated in the wrong thread ...

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

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.

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