* pr/17488:
  Polish "Create RestClient from a RestHighLevelClient if available"
  Create RestClient from a RestHighLevelClient if available

Closes gh-17488

This significantly rework the auto-configuration to reflect the order
in which things are expected. Rather than keeping a conceptual cycle
between the builder and the two inner classes that are processed first,
the configuration is now split in three parts:

* The builder that is required and common
* The configuration when the HighLevelClient is available
* The RestClient configuration when that's not the case

See gh-17488

See gh-17488

Fixes gh-17652

* pr/17736:
  Harmonize settings.gradle documentation in Gradle getting started guide
  Add missing repositories to snapshot configuration

Closes gh-17736

See gh-17736

See gh-17736

Closes gh-17676

Closes gh-17700

Closes gh-17639

* pr/17003:
  Clarify documentation about specifying main class

Closes gh-17003

See gh-17003

* pr/17691:
  Polish

Closes gh-17691

See gh-17691

Closes gh-17676

Update `UndertowServletWebServerFactory` so that only our own mime type
mappings are included. Prior to this commit both our mime mappings and
Undertow's default mime mappings would always be included.

Fixes gh-17687

Closes gh-17686

Closes gh-17685

Closes gh-17684

Closes gh-17683

Closes gh-17682

Closes gh-17681

Closes gh-17680

Closes gh-17679

Closes gh-17678

Closes gh-17677

Closes gh-17675

Closes gh-17674

Closes gh-17673

Closes gh-17671

Closes gh-17670

Closes gh-17669

Closes gh-17668