Remove noteblock pitch LUT

[KonaeAkira]

The problems with the current implementation using the LUT:

• Panics in case note is out of range. I don't think panicking for an invalid note is appropriate.
• The index-out-of-bounds check introduces a conditional branch.
• Requires memory access.

Some alternatives I explored: https://godbolt.org/z/8Txffr7d5

I decided to avoid all LUT-based implementations for this case because they either have a conditional branch or require the use of unsafe. Also, f32::exp2(x) compiles down to a single cvtsi2ss instruction on x86_64, so why not compute the pitch directly?

Computing the pitch is branchless and compute-bound instead of memory-bound. The CPU can probably find a way to slot the computation into its pipeline for free.