* Closes#2561
* Defines an extended subset of Cairo Assembly, following Section 5 of
[1].
* Adds the commands `juvix dev casm read file.casm` and `juvix dev casm
run file.casm` to print and run `*.casm` files.
* The tests cover CASM semantics. Some are "manual translations" of
corresponding JuvixAsm tests according to the JuvixAsm -> CASM
compilation concept.
