Mesh Convention Tools for Upstreaming to pyvale

[ScepticalRabbit]

Mesh Convention Module
Why: Riley expects that an input mesh will follow a certain convention to maintain correctness of shape function interpolation as well as visbility tests like back face culling.

What: Added a python module for checking and enforcing Riley's expected mesh convention before using meshes for rendering including:

• Functions for mesh surface extraction from volumetric meshes
• Functions for checking and enforcing the mesh convention
• Detailed and comprehensive test suite covering different types of meshes that violate the convention in different ways
• Updated all of Riley's data generation scripts, tests and pytests to use and enforce the mesh convention
• Added MESHCONVENTION.md to dev/ detailing Riley's convention

Other/Misc Additions & Improvements

• Reviewed and tidied up additional Riley python tools for meshio and uvs.
• Added a PYTHONSTYLEGUIDE.md to dev/

Additions to Riley's core zig rasteriser:
Global sub-pixel image buffers: Added global sub-pixel and global sub-pixel stripe buffer related to #17 . Sub-pixel buffer modes are verified against tile local renders in the min and psf test suites for correctness but the code itself is janky and needs an in-depth review for performance, consistency and redundancy against the rest of the codebase.
NOTE: For now sub-pixel buffers should be treated as an experimental feature under developement.

[ScepticalRabbit]

@james-panayis and @meganasampson I have raised a PR in pyvale that is now dependent on this being merged. If there are no review comments by Friday this week I am going to merge anyway and create a new Riley release.