* Closes#1614
* Implements the copy propagation transformation in JuvixReg and adds
tests for it.
* For this optimization to give any improvement, we need to run dead
code elimination afterwards (#2827).
* Closes#2562
Checklist
---------
- [x] Translation from JuvixReg to CASM
- [x] CASM runtime
- [x] Juvix to CASM pipeline: combine the right transformations and
check prerequisites
- [x] CLI commands: add target `casm` to the `compile` commands
- [x] Tests:
- [x] Test the translation from JuvixReg to CASM
- [x] Test the entire pipeline from Juvix to CASM
* Closes#2578
* Implements JuvixReg parser and pretty printer.
* Adds the `juvix dev reg read file.jvr` command.
* Adds the `reg` target to the `compile` commands.
* Adds tests for the JuvixReg parser.
