gh-103194: Fix Tkinter’s Tcl value type handling for Tcl 8.7/9.0 (GH-103846)

Some of standard Tcl types were renamed, removed, or no longer
registered in Tcl 8.7/9.0. This change fixes automatic conversion of Tcl
values to Python values to avoid returning a Tcl_Obj where the primary
Python types (int, bool, str, bytes) were returned in older Tcl.