Facilitate the import of multiple rego files in weaver registry check

[lquerel]

Currently, the --policy parameter allows specifying a single rego file. It would be useful to be able to import all rego files present in a directory. I see two possible approaches:

• Extend the existing --policy parameter to accept a directory and modify the internal logic of weaver to import, in this case, all files with the .rego extension.
• Add a new --policies parameter to specify a directory and automatically import all **/*.rego files.

I don’t have a strong preference for either approach. Feel free to share your opinion in the comments of this issue.