Set up CI to build with all supported versions of React Native

[tido64]

We need to make sure that all incoming changes are compatible with all currently supported React Native versions.

Pipeline Proposal

1. Check whether there has been any changes the last week.
   a. If there's been no changes, we end here. There is nothing to do.
   b. Otherwise, we continue with step 2.
2. Build against a reduced set of jobs (otherwise we will be spinning up 20+ jobs per version)
   a. Suggest to build only main jobs, i.e. Android, iOS, macOS, Windows, all debug, single architecture, no templates
   b. Even with reduced number of jobs, we're looking at 4 * N jobs where N is number of versions supported. Currently, this means 52 jobs.
   c. 52 jobs is a bit much to run on every PR, so we will do weekly builds instead.