Pex

This release fixes a few `pex3 lock create` bugs.

There was a regression introduced in Pex 2.1.122 where projects that
used a PEP-518 `[build-system] requires` but specified no corresponding
`build-backend` would fail to lock.

There were also two long-standing issues handling more exotic direct
reference URL requirements. Source archives with names not following the
standard Python sdist naming scheme of
`<project name>-<version>.{zip,tar.gz}` would cause a lock error. An
important class of these is provided by GitHub's magic source archive
download URLs. Also, although local projects addressed with Pip
proprietary support for pure local path requirements would lock, the
same local projects addressed via
`<project name> file://<local project path>` would also cause a lock
error. Both of these cases are now fixed and can be locked successfully.

When locking with an `--interpreter-constraint`, any resolve traversing
wheels using the `pypyXY` or `cpythonXY` python tags would cause the
lock to error. Wheels with this form of python tag are now handled
correctly.

* Handle `[build-system]` with no build-backend. (2064)
* Handle locking all direct reference URL forms. (2060)
* Fix python tag handling in IC locks. (2061)

This release fixes posix file locks used by Pex internally and enhances
lock creation to support locking sdist-only C extension projects that do
not build on the current platform. Pex is also updated to support
`--pip-version 22.3.1` and `--pip-version 23.0`, bringing it up to date
with the latest Pip's available.

* Support the latest Pip releases: 22.3.1 & 23.0 (2056)
* Lock sdists with `prepare-metadata-for-build-wheel`. (2053)
* Fix `execute_parallel` "leaking" a thread. (2052)

This release fixes two bugs brought to light trying to interoperate with
Poetry projects.

* Support space separated markers in URL reqs. (2039)
* Handle `file://` URL deps in distributions. (2041)

This release completes the `--complete-platform` fix started in Pex
2.1.116 by 1991. That fix did not work in all cases but now does.

PEXes run in interpreter mode now support command history when the
underlying interpreter being used to run the PEX does; use the
`PEX_INTERPRETER_HISTORY` bool env var to turn this on.

Additionally, PEXes built with the combination
`--layout loose --venv --no-venv-site-packages-copies` are fixed to be
robust to moves of the source loose PEX directory.

* Fix loose `--venv` PEXes to be robust to moves. (2033)
* Fix interpreter resolution when using `--complete-platform` with
`--resolve-local-platforms` (2031)
* Support REPL command history. (2018)

This release brings two new features. The venv pex tool now just warns
when using `--compile` and there is a `*.pyc` compile error instead of
failing to create the venv. Also, a new `PEX_DISABLE_VARIABLES` env var
knob is added to turn off reading all `PEX_*` env vars from the
environment.

* Ignore compile error for `PEX_TOOLS=1` (2002)
* Add `PEX_DISABLE_VARIABLES` to lock down a PEX run. (2014)

This is a very tardy hotfix release for a regression introduced in Pex