[🔧 esl-popup]: revisit esl-popup / esl-tooltip implementation (part 2 : follow-up)

[ala-n]

Followup of #2010

Both esl-popup / esl-tooltip modules are in the beta stage but already have non-beta usage on the projects.
The goal of the story is the following points:

• review and simplify esl-popup implementation, make it highly acceptable by code analyzing tools metrics
• revisit documentation and standard features of esl-popup
• check the esl-tooltip usages, and create a migration plan to make it public component:
  • esl-tooltip -> esl-note-tooltip
  • review esl-share-popup inheritance chain
  • create an actual esl-tooltip epic
• check init flow - styles (there is no default styles for empty tag)

Scope:

• immutable popup utilities
• Extra attributes feature
• A11ty: reuse focus mixins when ready