`repo upload --wip --no-verify .` should be an easy single command

### problem statement
pre-submit check is very useful. However, repo upload command with --wip flag is used for uploading the WIP CL to save the current state sometimes. running pre-check on such WIP change is just adding more psychological barrier to save that in the cloud, which increases the possibility to loss the change on some random causes (e.g. broken workstation, git operation mistake, etc...)

### proposed solution
introduce `lium cl save` command to save the work-in-progress change easily.

if the local change has multiple commits, it should be squashed just for uploading in some way (TBD), to avoid creating extra CLs accidentally.

maybe introduce `lium cl upload` for set the CL active for review.

### things to consider
- How to squash the commits automatically? (git v.s. Gerrit semantics)
- consider running presubmit tests for printing-out warnings...? (but it may slows down the cycle)
- automatic branch upstream fix (it's annoying...)