Allow --force-reinstall on uninstalled specs

[AntoinePrv]

Close #2634

[Hind-M]

Hmm, from a logical point of view, using force-reinstall should be used only on already installed packages (or is it in the sense of retrying to install because of previous failure?)

[AntoinePrv]

@Hind-M I agree this is debatable, but for now shouldn't we should restore current behavior.

I think it can be a use case to do mamba install --update-all --force-reinstall pkg1 pkg2 pkg3 ... (or even --file environment.yml) and not worry which packages are installed and which are not, especially since calling install in chunks is not the same at calling it once.
As a comparison, the equivalent pip install --ignore-installed works for uninstalled packages.