Handle Python 3.11 deprecation of PySys_SetPath and Py_SetProgramName

Python 3.11 deprecates PySys_SetPath and Py_SetProgramName.  The
PyConfig API replaces these and other functions.  This commit uses the
PyConfig API to provide equivalent functionality while also preserving
support for older versions of Python, i.e. those before Python 3.8.

A beta version of Python 3.11 is available in Fedora Rawhide.  Both
Fedora 35 and Fedora 36 use Python 3.10, while Fedora 34 still used
Python 3.9.  I've tested these changes on Fedora 34, Fedora 36, and
rawhide, though complete testing was not possible on rawhide due to
a kernel bug.  That being the case, I decided to enable the newer
PyConfig API by testing PY_VERSION_HEX against 0x030a0000.  This
corresponds to Python 3.10.

We could try to use the PyConfig API for Python versions as early as 3.8,
but I'm reluctant to do this as there may have been PyConfig related
bugs in earlier versions which have since been fixed.  Recent linux
distributions should have support for Python 3.10.  This should be
more than adequate for testing the new Python initialization code in
GDB.

Information about the PyConfig API as well as the motivation behind
deprecating the old interface can be found at these links:

https://github.com/python/cpython/issues/88279
https://peps.python.org/pep-0587/
https://docs.python.org/3.11/c-api/init_config.html

The v2 commit also addresses several problems that Simon found in
the v1 version.

In v1, I had used Py_DontWriteBytecodeFlag in the new initialization
code, but Simon pointed out that this global configuration variable
will be deprecated in Python 3.12.  This version of the patch no longer
uses Py_DontWriteBytecodeFlag in the new initialization code.
Additionally, both Py_DontWriteBytecodeFlag and Py_IgnoreEnvironmentFlag
will no longer be used when building GDB against Python 3.10 or higher.
While it's true that both of these global configuration variables are
deprecated in Python 3.12, it makes sense to disable their use for
gdb builds against 3.10 and higher since those are the versions for
which the PyConfig API is now being used by GDB.  (The PyConfig API
includes different mechanisms for making the same settings afforded
by use of the soon-to-be deprecated global configuration variables.)

Simon also noted that PyConfig_Clear() would not have be called for
one of the failure paths.  I've fixed that problem and also made the
rest of the "bail out" code more direct.  In particular,
PyConfig_Clear() will always be called, both for success and failure.

The v3 patch addresses some rebase conflicts related to module
initialization .  Commit 3acd9a692dd ("Make 'import gdb.events' work")
uses PyImport_ExtendInittab instead of PyImport_AppendInittab.  That
commit also initializes a struct for each module to import.  Both the
initialization and the call to were moved ahead of the ifdefs to avoid
having to replicate (at least some of) the code three times in various
portions of the ifdefs.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=28668
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29287

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