[keycloak-dev] PR - Remove Keycloak version from resource paths

Today, Keycloak includes the Keycloak version in resource paths to make sure browsers fetch the new versions of resources after an upgrade. It is not good practice to expose the version of software on public endpoints, as such we need to change this behavior. To achieve this I've updated the migration model to create a random 5 character URL friendly id that is persisted in the database, which is then used in place of the Keycloak version. That means there will be a unique resource version for each installation of Keycloak, which is updated when Keycloak is upgraded. To prevent conflicts the previous versions are not deleted from the migration model. PR is here: https://github.com/keycloak/keycloak/pull/6473