Deprecated propagation of extension methods in docs

[nicolasstucki]

Compiler version

3.2.1

Minimized code

Marking a single method in an extension clause as deprecated makes them all deprecated in the docs. In this example we have valueOrError that is deprecated, but the docs also say that show, matches, value and valueOrAbort are deprecated

https://github.com/lampepfl/dotty/blob/cfcdefa50c26c3f42893cc980ef92662aa9ac392/library/src/scala/quoted/Quotes.scala#L28-L70

Output

Expectation

Should split the extension group into deprecated and non deprecated.

[nicolasstucki]

A minimal example would be the following.

extension (x: Int) 
  def a: Int = ???
  @deprecated def b: Int = ???

The docs should not show a as deprecated.

[nicolasstucki]

There might be a similar issue for @experimental in #16310.