Provide PyOxidizer binaries

[Schamper]

This PR adds CI for building PyOxidizer binaries for Windows, macOS, Linux (GNU) and Linux (musl).

The Linux musl build currently depends on a forked PyOxidizer (https://github.com/fox-it/PyOxidizer/tree/esxi-compatibility) because of indygreg/PyOxidizer#725. The fork also includes a workaround for ESXi.

The Linux GNU build is built in a manylinux2014 container to ensure an old libc version for compatibility.

The macOS build combines a x86_64 and aarch64 binary into a single universal2 binary for compatibility on both Intel and Apple Silicon Macs.

A separate list of dependencies is currently maintained in pyoxidizer.bzl because there are no appropriate dependency bundles available in acquire right now. minio is included for uploading to cloud storage, but unfortunately pycryptodome is not yet included. It should be possible to include it but I couldn't get it working across all OS variants right now, so that could be a future improvement. The way to go here is likely a filesystem fallback on an accompanied lib directory, but for some reason this broke the embedded msgpack. PyOxidizer should also be able to recompile an extension into itself but I did not look into this yet.

The pyoxidizer.bzl file also includes comments explaining how to build manually, as well as how you could modify the embedded configuration.

Ideally we add these binaries as files into the releases, but I wasn't sure what the desired CI trigger would be for that, so I've put it on tags for now. For this reason, the PyOxidizer also currently downloads the latest stable acquire from PyPI instead of copying from the local source repository.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 44.60%. Comparing base (f5b50b6) to head (122daee).
Report is 6 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #109      +/-   ##
==========================================
+ Coverage   44.36%   44.60%   +0.24%     
==========================================
  Files          26       26              
  Lines        3316     3394      +78     
==========================================
+ Hits         1471     1514      +43     
- Misses       1845     1880      +35     

Flag	Coverage Δ
unittests	44.60% <100.00%> (+0.24%)	⬆️

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