Allow users to override built-in templates

[FroMage]

This is useful at least for:

• Login form
• Backoffice

[gza]

True. Specially when doc says to make your own login form : https://docs.quarkiverse.io/quarkus-renarde/dev/security.html#custom_authentication_with_jwt

The following is a bit out of scope, but this issue is an example of more general problem: There is too much discrepancies in doc and too much undocumented behavior.

As a Java beginner, Renarde seems to be the ideal framework. But after few days coding, reading docs and even Renarde's source code, I'm starting to think that it will be faster and less risky to learn framework and libs Renarde uses itself.

I do think Renarde is missing its target: accelerate and simplify development.

Anyway, I will give it another chance.

[FroMage]

The more users this gets, the better it will get with feedback and solving more use-cases and getting pull-requests from users.
I wish I had more time to solve all these issues, but I don't always. If you want to improve the docs or fix anything, it could bring things forward :)