We have multiple pre-computed constant hash tables that all use the same
quadratic probing algorithm.
Add a constant_hash Rust module to match the meta/constant_hash.py module.
Move the simple_hash() function into constant_hash. Its Python equivalent is in
the constant_hash.py module.
Rather than switching on instruction formats to discover the destination of a
branch, use the analyze_branch method which returns a BranchInfo enum with just
the relevant information.
This makes CFG algorithms independent of future instruction formats for
branches. Only analyze_branch needs to be updated when adding a new format.
