CLI Text Styles and pre-commit configuration

[victorgarcia98]

Closes #603

• CLI Text Styles defined in class ColorCode.
• Updating deprecated flexmeasure command in the documentation.
• Removing language_version from the pre-commit configuration.

[Flix6x]

I think the name of this development branch is a bit confusing. @nhoening what do you suggest? Rename and recreate this PR?

[nhoening]

I think the name of this development branch is a bit confusing. @nhoening what do you suggest? Rename and recreate this PR?

I believe the branch name is not that relevant, what we want to control is the commit message of the merge commit.

[nhoening]

Great work. I got a few requests, but nothing serious.

Out of interest - have you checked how click.UsageError is styling the error messages?

[coveralls]

Pull Request Test Coverage Report for Build 4488267179

• 11 of 120 (9.17%) changed or added relevant lines in 9 files are covered.
• 4 unchanged lines in 3 files lost coverage.
• Overall coverage increased (+0.04%) to 64.842%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
flexmeasures/cli/testing.py	0	2	0.0%
flexmeasures/cli/data_edit.py	1	4	25.0%
flexmeasures/cli/jobs.py	1	5	20.0%
flexmeasures/cli/monitor.py	1	6	16.67%
flexmeasures/cli/db_ops.py	1	11	9.09%
flexmeasures/cli/data_delete.py	1	19	5.26%
flexmeasures/cli/data_show.py	1	20	5.0%
flexmeasures/cli/data_add.py	1	49	2.04%

Files with Coverage Reduction	New Missed Lines	%
flexmeasures/cli/data_add.py	1	31.81%
flexmeasures/cli/db_ops.py	1	42.17%
flexmeasures/cli/data_show.py	2	24.23%

Totals
Change from base Build 4479947128:	0.04%
Covered Lines:	6869
Relevant Lines:	9858

---

💛 - Coveralls

[victorgarcia98]

I'm just pushed the changes you requested. Moreover, I have harmonized the raise of exceptions (all raise click.Abort -> raise.Abort()).

By the way, I think we need to standardize the way we exit the CLI commands in case of an error. In some places, there is just a return, which exists the code with status code = 0, and others where it raises the click.Abort() exception, which exists the code with status code = 1). The cases where there were returns what were clear errors, I've replace the return by raise click.Abort().

Please, let me know if it is fine like this or we should distinguish between 'code errors' (exceptions) and 'operational errors' (invalid operations).

[nhoening]

I approve, just one small fix left.

The danger with this one of course is that our test coverage of the CLI commands is very bad. We have flake8 etc for a little help.
It's easy to overlook one small mistake and ruin a command until someone tries it.

How many commands did you try manually, to see if they work?