[Qt-creator] RFC: Dropping use of Python 2.x in Creator's debugger bridges

[apoenitz]

Hi all.

As you may know, Qt Creator uses some Python based abstraction layer to
talk to the actual debugger "backends" (GDB, LLDB, CDB). This layer
currently supports both Python 2.x and 3.x. For GDB and LLDB the actual
version of Python used to execute that code is determined at runtime
by the actual GDB and LLDB setups in the system.

This is a workable solution, but requires a few hacks that eat CPU cycles
and deprive us from using a few nice-to-have features of Python 3 in the
abstraction layer.

So I'd like to drop official support for Python 2.x based setups of GDB
and LLDB. The plan would be to "archive" the current contents of
share/qtcreator/debugger/ to, say, share/qtcreator/debugger-python2 and
drop support for Python 2.x in share/qtcreator/debugger/.

As there won't be changes on the protocol between Qt Creator and the
interface layer, people /needing/ a GDB or LLDB that uses Python 2.x
could manually undo that change for themselves locally (plain text files,
no compilation), i.e.  nobody on "old" setups will be completely lost
("old" == LLDB before ~2020, GDB before ~2014, both depending on concrete
setup).

I personally think this would be acceptable in all use cases I am
currently aware of, but as I do not know all use cases, this here is
meant to give people a chance to veto. Personal mail is fine.

If there's no objection until the end of the month I'll implement that
change for Qt Creator 13 (due March 28, 2024)

Andre'