XWIKI-11157: Provide more Flamingo Themes by default.

Update tests.
XWIKI-11371: Detect the webjar version instead of hard-coding it
* Small improvements (thanks to Vincent and Thomas)
XWIKI-11372: Add support for evaluating WebJar resources that contain Velocity code
* Improve the test and the comments (thanks to Vincent)
XWIKI-11371: Detect the webjar version instead of hard-coding it
* Small improvements (thanks to Vincent and Thomas)
XWIKI-11372: Add support for evaluating WebJar resources that contain Velocity code
* Improve the test and the comments (thanks to Vincent)
Merge branch 'master' of github.com:xwiki/xwiki-platform into feature-tree