Add installation-dir to customize where the installers are installed to

[isuruf]

This is useful for self-hosted runners where we can change the installation directory to the workspace directory to allow automatic cleaning up of the miniforge/miniconda environments.

[isuruf]

cc @finnagin

[jaimergp]

Just one comment about the name chosen for now. Implementation looks ok. We should add an example test to make sure this works as intended.

[jaimergp]

I'm inclined to using installation-directory here instead. The rest of the options in this project seem to be using no abbreviations (e.g. we fully spell environment instead of env).

[goanpeca]

Hi @isuruf, indeed I agree with @jaimergp comment, we should try to use full names :)

[goanpeca]

Thanks for working on this @isuruf

Could we add information on this usage on the README?

Also could we add some sort of workflow to test this?

If this only makes sense for self hosted runners, maybe we could add something on this PR #301 ?

Comments were addressed

[jaimergp]

Thanks!