kernel/ksupport: add linalg functions

[AR-PyT]

ARTIQ Pull Request

Description of Changes

Adds runtime implementation of np.linalg/sp.linalg functions (M-Labs/nac3#478 and M-Labs/artiq-zynq#309) Depends on #2526

Related Issue

Type of Changes

	Type
✓	:sparkles: New feature

Steps (Choose relevant, delete irrelevant before submitting)

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Code Changes

• [x] Run flake8 to check code style (follow PEP-8 style). flake8 has issues with parsing Migen/gateware code, ignore as necessary.

Licensing

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[sbourdeauducq]

Is this tested? I don't think this is going to work without adding nalgebra to cargo. If this is hassle because Rust, we can also skip support for nalgebra on risc-v devices, since it's probably quite slow there anyway.