[wip] [mypyc] feat: unroll certain for loops with known params

[BobTheBuidler]

This PR, when finished, will unroll any for loops that iterate across a set of values which are known at compile time

This allows us to entirely bypass any iteration overhead and keep more things in C-space

It also does the same when iterating across the values of any mypyc-defined tuple types, whether the values are known at compile time or not

The generated C code will be longer but more readable with less branching and no iterator overhead, will offer the C compiler many more opportunities for optimization

It's probably best for everyone if these 2 PRs are merged before anyone spends time looking at this one:

• feat(test): mypyc tests for container creation from range #19511
• [mypyc] feat: cache len for iterating over immutable types and expressions with length known at compile time #19503