* Add shelltests for `juvix repl`
* repl: Compute entrypoint root when loading a file
Previously the REPL would use app root (which could be the current
directory or the project root of the initially loaded file). Thus files
in a different project could not be loaded.
The entrypoint root must be computed each time a new file is `:load`ed.
Adds shell-tests for REPL commands
* Move preludePath to Juvix.Extra.Paths