[Misc] Force the docker image releaser to update the JDBC driver versions (so that they're up to date)

+ upgrade the MYSQL JDBC driver to version 8.0.28

[Misc] Use a better (more specific) tomcat image tag so that if tomcat changes the jdk version for tag "9", we won't be affected

[Misc] Remove my name and email now that the module is in the XWiki GitHub Organization and this maintained by the XWiki Committers

* Revert the MySQL upgrade because of issues for 12.10.x and 13.2.x branches

* Also update the MySQL driver from 8.0.22 to 8.0.23

* Verify the MySQL driver download to avoid man in the middle attacks

* And switch to AdoptOpenJDK 8.x for XWiki 10.x (since XWiki 10.x doesn't support Java 11)

* More progress, still not working. I have an issue with "jdbc:postgresql://replacecontainer:5432/replacedatabase" not working and generating " Caused by: java.net.UnknownHostException: xwiki-postgres-db"
* Added ascii art in Dockerfile
* Renamed containers so that we can run several xwiki images on the same machine without conflict

* Use a better name for the property (thanks to Tianon)

* More progress, still not working

* Prepare the field by generifying the templates/build and docker files

 XDOCKER-10: Cannot change database name
* Add leftover that was forgotten

* Implement a simple Gradle build to generate the various versions/variants.

[Misc] Improve doc (was committed as part of "XDOCKER-13: Add an image tag for XWiki 9.0 and publish on dockerhub" on the 9.x branch)

[Misc] Fix wrong VOLUME location issue introduced when I refactored the code to depend on the tomcat image instead of on debian jesse directly...