Release utils
# What does this PR do?

This PR adds utilities to help with the release process and four make commands to use them easily:

1. `make pre-release` will do all the necessary steps prior to the commit with the release tag (put the right version in all the good places and clean the README from the references to the master documentation).
2. `make post-release` will do all the necessary steps after the release has been made (put the right dev version in all the good places and add the latest version in the deploy doc/doc navbar)
3. `make pre-patch` will do all the necessary steps prior to the commit with the release patch tag (put the right version in all the good places).
4. `make post-past` will do all the necessary steps after the patch release has been made and we are back on master (put the right dev version in all the good places and add the latest version in the deploy doc/doc navbar)