Support for pull request by language

**Is your feature request related to a problem? If so, please describe.**

We are starting to set up in XWiki a new process when a new language is introduced in the platform because we need to perform some checks to ensure the language will be properly supported by our search engine etc.
The problem is that all contributions made in Weblate are currently sent in a unique pull request on our repository, so a pull request mixes changes related to multiple language. If we need to perform checks for adding a new language (that we see because of a pull request submission), it means that we'll block all other changes until we performed the checks (and possibly some changes in our code).

**Describe the solution you'd like**

It would be nice to be able to receive different pull requests depending on the language translated. It would prevent us blocking contributions in other languages when a new language is added. It would probably also help reviewing the contributions: we mainly do the review process by checking the PR.

**Describe alternatives you've considered**

Right now we don't see many alternatives: we are gonna block the PR until we're ready to merge them.