[wip] [mypyc] feat: quasi-constant folding for DictExpr and TupleExpr

[BobTheBuidler]

This is WIP, I just needed the runners to run. This PR strives to accomplish all of the following:

We should be able to constant fold an expression like (str, int) for use cases such as isinstance(obj, (str, int)) . Currently, the tuple is constructed each time. It should be feasible to do this with any tuple comprised of literals, builtin types, and/or final values of any kind.

It should also be possible to "constant fold" a LOC such as:

requests.get(some_url, headers={"k0": "v0", "k1": "v1"})

We can't simply create a dictionary constant since dicts are mutable and we don't know what's going to happen in the called function, but we can hold a template dict in memory and PyDict_Copy it when it's time for use. This skips the hashing and any resizing during construction, and simply takes the hash table from the existing dict instead, which will be (possibly much) quicker than constructing from scratch each time.