Make size of TOS cache configurable

TOS caching was introduced by https://github.com/python/cpython/issues/135379, but it only supports a fixed number of registers.
We should make it configurable, so that we can choose the optimum number of registers for any hardware/OS combination.

Probably the simplest way to do this is to generate executor cases and stencils code for up to the overall maximum number of registers, and guard each case/function with an #if MAX_CACHED_REGISTER > N where N is the number of registers needed for that variant.
Some cases/functions will also need to guarded for when MAX_CACHED_REGISTER is too low.

For example the ideal number of output registers for _BINARY_OP variants is 3.
For machines where MAX_CACHED_REGISTER < 3, we will need to generate variants with outputs < 3, but we want to exclude those variants for machines with MAX_CACHED_REGISTER >= 3

Overall this could result in generating a lot more code, probably more than double, but if MAX_CACHED_REGISTER is unchanged then the executable size should also be unchanged.

If we increase the MAX_CACHED_REGISTER to 4 or 5 we would expect the stencils and supporting tables to increase by ~35% and ~80% respectively (growth being a bit more than linear as some instructions have N**2 variants)

Linked PRs

• gh-145830

先閱讀 issue 135379 以及其中連結的 PR 145830 中的工作，接著追蹤此處描述的 TOS 快取暫存器產生與 stencil 路徑。完成的標準是，MAX_CACHED_REGISTER 能為不同的硬體與 OS 組合選取合適的變體，同時在未變更時維持所述的可執行檔大小行為。