Revisit Nuitka and PyOxidizer

[Infernio]

PyInstaller's binaries are basically just self-extracting ZIP archives. The problem with that is that it has become quite slow - especially if your temporary directory (which is where the extracted files go) is on an HDD - due to multiple reasons:

• We've added several optional dependencies, which obviously get included in the Dropbox/Nexus builds.
• Some of our dependencies have significantly grown in size over time as they added features.
• We've begun using more features from some of our existing dependencies/the stdlib, which means more modules and pyd's have to be included (e.g. wx.svg -> _nanosvg, etc.)
• Python 3.11 has significantly increased the size of generated bytecode due to the new bytecode cache entries - that alone bumped WB EXE size up by 4MB.

I've investigated Nuitka a bit (it seems to now support building a single EXE). The build takes quite a long time, but the resulting EXE does not suffer from the same startup issue (which makes sense - it truly builds an executable, rather than a self-extracting ZIP). scratch that, the startup speedup seems to only happens in onedir mode, not in onefile mode. Which makes sense, maybe we should first investigate onedir mode in PyInstaller? One problem is that pkgutils.iter_modules does not seem to work with it. Another is that it appears to need a .cmd file. And finally, it does not support Python 3.11 yet.

I also want to check back in with PyOxidizer and see how that project is coming along.

312+ territory, plus we'll probably want to keep this optional if we go with Nuitka so that we're not blocked if another Python 3.11-like scenario comes where Nuitka will take a long time to upgrade.

Followup to #491, obsoletes #609.

[lojack5]

Been checking in periodically with Nuitka myself, that would be an amazing option. It'd be a large speed bump due to the transpiling. But yep, it always seems to be 2 or more versions behind the current CPython (looks like only 1 version behind at the moment though!)

3.12 so far isn't bringing any super high features, but it's still in alpha. If it doesn't end up bringing anything big we want I'd say wait for 3.11 support on Nuitka.