Feat: Implemented type propagation

[JuliaPoo]

This pull requests contains:

1. Additional features to the DSL and corresponding changes in bytecode.c for the type propagation
   • DSL has type annotations referencing the local and const arrays
   • DSL allows annotating local array effect

Example:

// The stack effect `value` is type annotated by an index into the const array: `consts[oparg]`
inst(LOAD_CONST, (-- value : consts[oparg])) {
    value = GETITEM(consts, oparg);
    Py_INCREF(value);
}

// The local array effect is annotated after the stack effect as `locals[oparg] = *value`, 
// `*value` indicating that the variable is a stack variable (as opposed to a literal like `PyLong_Type`)
inst(STORE_FAST, (value --), locals[oparg] = *value) {
    SETLOCAL(oparg, value);
}

2. Generated the type propagator:
   • The type propagator is located at tier2_typepropagator.c.h which is inlined into tier2.c. This file deals with type propagation across all tier2 bytecode except for BB_TEST_IF_FALSE_OR_POP and BB_TEST_IF_TRUE_OR_POP because it's stack effect is dependent on branch taken
   • Type propagation happens on the DISPATCH() call in _PyTier2_Code_DetectAndEmitBB, which accounts for all tier2 bytecode except branch instructions
   • Type propagation for branch instructions happens within emit_logical_branch, which deals with type propagation except for the two above mentioned instructions
   • Type propagation for the last two instructions are dealt within BB_BRANCH, where both BB_TEST_IF_FALSE_OR_POP and BB_TEST_IF_TRUE_OR_POP sets a flag gen_bb_requires_pop during runtime which gets used in BB_BRANCH to perform the corresponding pop on the type context for the next BB.

Other misc (but important) changes:

1. type_context is now its own struct
2. _PyTier2_Code_DetectAndEmitBB no longer makes a copy of the type_context and instead modifies the type context passed into it. Callers of this function should make a copy if needed.

Future work:

1. Add more annotations/type specialised instructions to the DSL, there's a chance the cases generator breaks bcuz of a bug from the code introduced here
2. Memory used by a type_context from a BB who's target branches have all been generated can be reused without additional allocations, since said BB doesn't require a type_context anymore.