add copy to move_and_delete

[juliettelavoie]

Pull Request Checklist:

• [ ] This PR addresses an already opened issue (for bug fixes / features)
  • This PR fixes #xyz
• [ ] (If applicable) Documentation has been added / updated (for bug fixes / features).
• [x] (If applicable) Tests have been added.
• [x] This PR does not seem to break the templates.
• [x] HISTORY.rst has been updated (with summary of main changes).
  • [x] Link to issue (:issue:number) and pull request (:pull:number) has been added.

What kind of change does this PR introduce?

*Many small change to help my workflow work better.

• Adding copy to move_and_delete is useful for taking everything in a directory and adding files inside an already existing structure with other files.
• Adding var_as_str to get_cat_attrs is useful to automatically write paths without parenthesis. Before: ('tasmin',)_CanESM5.zarr After: tasmin_CanESM5.zarr`
• Adding restrict_years to compute_indicators is useful to reproduce exactly xclim's output. I want to redo exactly somehting that was done pre-xscen. The default is still to cut the nans, but this makes it possible to keep them.
• Add documentation to template 1.

Does this PR introduce a breaking change?

no ( if you had a workflow writting a path with the tuple, it will be broken but I doubt anyone did that).

Other information:

[juliettelavoie]

For comments on template docs, see PR#235. If there is no more comments on the rest, I will merge.

[RondeauG]

For comments on template docs, see PR#235. If there is no more comments on the rest, I will merge.

Fine with me!