DO NOT MERGE ! - Extend web components GSGMF 1650

[ger-benjamin]

For: GSGMF-1650

See also (updated doc) camptocamp/c2cgeoportal#8911

See commit message to understand the history of changes.

I was able to:

• Override methods in a lit component
• Override methods in an AngularJS component (still works)
• Extends a lit component
• Override methods of a model
• Override methods of a "service"
• Set css of a lit component via the vars (long but no need to override elements)
• Set the css inside the overriden element itself (quicker for overridden elements)
• Set the css by appending a style in a selected element querySelector (querySelector('...').shadowRoot.appendChild. It work on multiple nested level of Shadow DOM as our component are in an open mode. Should also work with a CSSStyleSheet)

Well, I had no real problem to do the changes.

Maybe it would be great to split long render method to multiple small methods.
(As it should be already the case for other methods and especially long constructor (not modifiable))

Result of my changes:

[ger-benjamin]

No need to merge, only a demo POC. I close.