Use Semantic Versioning for module releases and branches

Problem/Motivation

The module uses branches with Drupal Core version. Since time ago modules should use Semantic Versioning for the releases naming.

See https://www.drupal.org/docs/develop/git/git-for-drupal-project-maintaine... →

Proposed resolution

Change the main development branch to 1.x.

Because there are no releases yet the first release should be 1.0.0.

Remaining tasks