Re-implement performance metrics in C++

[bitbrain]

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read https://github.com/bitbrain/beehave/discussions/285 for the announcement for Beehave 3.0

Performance metrics are currently implemented in GDScript and require a hacky setup via autoloads. Reimplement this in C++ for cleaner implementation.

[bitbrain]

Use this branch as a base: https://github.com/bitbrain/beehave/tree/v3