- Introduce new `Path` type and an array of build paths on the build context.
- Resolve input and output paths/files early (before parsing).
- Error early if inputs are missing or outputs are directories.
- Plumb new file path generation into linker stage instead of its adhoc method.
TODO:
- Remove more adhoc file path generation in parser and linker stage.
- Make intermediate object file generation use new path system.
- Round out and robustify Path helper functions.
Inits `o->value` in `check_expr_base_internal()` so doesn't accidentally
use last (the proc lit was being set to that of previous string)
Adds test to "tests/issues" and changes CI to use new "run" shells
Changes lb_build_if_stmt() to return null lbValue if condition is
cmpAnd, cmpOr or non-const neg and check in lb_build_if_stmt()
to avoid short circuiting if that's the case
Adds test to "tests/issues" and adds step in CI to check this dir
