Reorganise project branches and workflows

[vaadin-miki]

The following structure should work:

• master should only be used for released versions, it is expected to be stable and safe to use
• development should be main branch into which code goes, all tests pass, but the behaviour may be quirky; it has the next version + snapshot modifier in it
• release-X.Y.Z should branch off of development, targetting master, when the release is ready; upon creating that branch all tests must be done, but before that happens a workflow should set versions of superfields and superfields-parent to whatever X.Y.Z is; once a pr is merged into master, if possible, a tag should be made automatically to it, so that a new release is done

Ticket branches should still start with a ticket number, followed by -scope of work. More than one ticket can be worked on at the same time in such branch. If it is known at the time of starting work, branch name should be A-B-scope (where A, B, are ticket numbers).

If automation is not possible to the degree described above, keep the current model.

Also, create a wiki page explaining the branches and how to contribute to this project.