Remove cython

[mpurnell1]

Description
This is the parent PR which fully removes cython from openpilot (part 10 of 10). This potentially opens the door to reopening and completing commaai/opendbc#2799
It depends on the following PRs:

• params: Move all Cython to Python and C++ #36829
• transformations: move Cython to pure Python #36830
• pandad: Move all Cython to Python and C++ #36831
• Move ipc cython to Python and C++ msgq#662
• commonmodel: Move all cython to cc #36832
• cereal: update msgq imports #36833
• Move ekf_sym cython to cc rednose#53
• locationd: Update outdated reference after cython removals #36837
• third_party/acados: Remove cython and import dynamically instead #36834

Actual changes in this PR:

• Remove all references to deleted cython code
• Remove cython as a project dependency

TODO:

• Remove the submodule changes in this branch once the corresponding PRs are merged
• Install branch on-device and obtain route

Verification
op test before these changes:

op test after these changes:

[adeebshihadeh]

FYI, I think this is directionally correct, but you should be aware:
a) this is a very big project that should be done piecemeal
b) i'm not even sure we can totally get rid of the Cython

I don't think we want to write our own Python extensions instead (~70% sure about this). I think we should start by porting more to native Python, like #35854, then after all that's done, we decide what to do with the remaining C++.

[mpurnell1]

Thanks for the feedback! I did my best to break it up into separate PRs that could all be merged atomically, leaving this PR until the very end. At your recommendation, I updated the first three PRs (#36829, #36830, and #36831) to convert the Cython mainly to Python instead of C++. Hopefully that's closer to what you're looking for. If so, I'll get started on converting the remaining PRs, including this one.

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