autosubmit create returning 1 even though it succeeds

[kinow]

Found while testing #2123 for @orioltinto. I had an autosubmit create a000 && autosubmit inspect a000, and the RHS part was not being evaluated.

I checked and autosubmit create was not logging any errors but it was returning 1. Looking at the code, it's because def create(...) returns a bool instead of an int. Enabling mypy + type hints might be the cheapest way to find issues like this, or we review everything or write tests for the missing parts.

I have the fix done locally, but will prepare a small test later and submit a pull request (will focus on #2104 as that has higher priority).

[kinow]

Looks like there are other functions of commands that also return bool, while some still return int...