This is the second in a series of pull requests to implement an Index for UTXO set statistics.
This pull request adds a Python implementation of Muhash3072, a homomorphic hashing algorithm to be used for hashing the UTXO set. The Python implementation can then be used to compare behavior with the C++ version.
test: Move modinv to util and add unit test
test: Add Python MuHash3072 implementation to test framework
test: Add basic Python/C++ Muhash implementation parity unit test
test: Add chacha20 test vectors in muhash
This is a backport of core#19105
Backport note: the C++ implementation will be merged much later (core#19055)