Don't ignore modules tool when using --fetch

[Flamefire]

The modules tool is required when resolving (at least) external dependencies.

Fixes #4298

I guess the intention was to ignore installed modules for --fetch as I had to change the condition for keep_available_modules for the test to pass as it would otherwise not fetch for installed modules which I'd guess is not intended.

For that I also changed the keep_available_modules = keep_available_modules or ... style to any([...]) which I think is easier to read and format. The 2 dry-run and inject-checksum options are on the same line on purpose

[boegel]

The intention of ignoring the modules tool is that --fetch can be used even if no modules tool is available at all (for example on your laptop), see also the original implementation in #2457

[Flamefire]

I implemented an alternative in #4308 with the approach I described in #4298 (comment)