refactor: move memory out of cpu

The cpu will have external memory,
that will allow for better testing
capabilities, and also makes more
sense.

refactor: change program mem to file prog mem

fix(register_file): output register if addr not zero

feat: add cpu top level entity

feat: add control_unit wrapper over instruction_decoder

chore: add cpu types for various sources

Better orientation by name instead of
number

feat: add program counter

feat: add program memory

chore: ignore obj_dir, vcd outputs

fix: alu arithmetical shift

Has to have signed as arguments

feat(decoder): implement memory mask, conditional jumps

refactor: parametrize register file

chore: move default case

fix: make rd1, rd2 in register_file regs

feat: add instruction decoder

chore: formatting

feat: add basic ram, alu, and register file

chore: add gitignore

chore: add flake environment