Use pyo3 to provide a direct python interface.

[cjordan]

This is not ready to be merged!

This commit contains code that could allow pymwalib to be deprecated. Work to do and considerations:

• The Python module name becomes mwalib and can't be pymwalib (it needs to match the name of the Cargo package)
• I've copied pymwalib examples over, but they currently don't work because (1) imports need to be updated and (2) there are other differences
  • The check_mwalib_version function shouldn't be needed anymore; no libmwalib.so file is needed to run the pyo3 Python code.
  • Installation instructions should be added
  • (I usually just use maturin develop --release -b pyo3 --features=python --strip)
• maturin (the Python tool used to install the Rust code as a Python package) likes you to have a pyproject.toml file (or something like this); this should be added.
• Performance should be checked. Maybe it's worse?
• CorrelatorContext should be good to go, but I haven't put in any work for VoltageContext
• Add function signatures for nice help texts in Python
• Provide CI-pre-built wheels for compatible python versions (3.7+)?
  • Examples to do this exist in hyperbeam

So, there's a lot of stuff to be done, but, it should mean less work long term because pymwalib needs to be kept in sync with mwalib.

[codecov[bot]]

Codecov Report

Patch coverage: 90.13% and project coverage change: -0.09% :warning:

Comparison is base (d7ff687) 96.50% compared to head (4d6f1de) 96.42%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #57 +/- ## ========================================== - Coverage 96.50% 96.42% -0.09% ========================================== Files 35 35 Lines 14883 14953 +70 ========================================== + Hits 14363 14418 +55 - Misses 520 535 +15 ``` | [Files Changed](https://app.codecov.io/gh/MWATelescope/mwalib/pull/57?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=MWATelescope) | Coverage Δ | | |---|---|---| | [src/antenna/mod.rs](https://app.codecov.io/gh/MWATelescope/mwalib/pull/57?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=MWATelescope#diff-c3JjL2FudGVubmEvbW9kLnJz) | `96.77% <ø> (ø)` | | | [src/baseline/mod.rs](https://app.codecov.io/gh/MWATelescope/mwalib/pull/57?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=MWATelescope#diff-c3JjL2Jhc2VsaW5lL21vZC5ycw==) | `86.95% <ø> (ø)` | | | [src/coarse\_channel/error.rs](https://app.codecov.io/gh/MWATelescope/mwalib/pull/57?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=MWATelescope#diff-c3JjL2NvYXJzZV9jaGFubmVsL2Vycm9yLnJz) | `0.00% <ø> (ø)` | | | [src/coarse\_channel/mod.rs](https://app.codecov.io/gh/MWATelescope/mwalib/pull/57?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=MWATelescope#diff-c3JjL2NvYXJzZV9jaGFubmVsL21vZC5ycw==) | `97.24% <ø> (ø)` | | | [src/convert/mod.rs](https://app.codecov.io/gh/MWATelescope/mwalib/pull/57?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=MWATelescope#diff-c3JjL2NvbnZlcnQvbW9kLnJz) | `98.14% <0.00%> (-0.37%)` | :arrow_down: | | [src/correlator\_context/mod.rs](https://app.codecov.io/gh/MWATelescope/mwalib/pull/57?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=MWATelescope#diff-c3JjL2NvcnJlbGF0b3JfY29udGV4dC9tb2QucnM=) | `98.36% <ø> (ø)` | | | [src/error.rs](https://app.codecov.io/gh/MWATelescope/mwalib/pull/57?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=MWATelescope#diff-c3JjL2Vycm9yLnJz) | `100.00% <ø> (ø)` | | | [src/fits\_read/error.rs](https://app.codecov.io/gh/MWATelescope/mwalib/pull/57?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=MWATelescope#diff-c3JjL2ZpdHNfcmVhZC9lcnJvci5ycw==) | `100.00% <ø> (ø)` | | | [src/gpubox\_files/error.rs](https://app.codecov.io/gh/MWATelescope/mwalib/pull/57?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=MWATelescope#diff-c3JjL2dwdWJveF9maWxlcy9lcnJvci5ycw==) | `0.00% <ø> (ø)` | | | [src/gpubox\_files/mod.rs](https://app.codecov.io/gh/MWATelescope/mwalib/pull/57?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=MWATelescope#diff-c3JjL2dwdWJveF9maWxlcy9tb2QucnM=) | `95.69% <0.00%> (-0.52%)` | :arrow_down: | | ... and [16 more](https://app.codecov.io/gh/MWATelescope/mwalib/pull/57?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=MWATelescope) | |

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