RFR: 8340785: Update description of PassFailJFrame and samples [v2]

[Alexey Ivanov]

> I re-worked the entire description of `PassFailJFrame`:
> 
> Add description of what UI elements it provides and how to interact with them.
> Add anchors for linking to the sections.
> 
> Use `{@snippet}` instead of `<pre>{@code}</pre>` for sample code.
> Use method references instead of lambdas in samples.
> Document required jtreg tags to use `PassFailJFrame`.
> Rename `SampleOldManualTest` to `ObsoleteManualTest`.
> 
> Provide an overview of `Builder` methods to configure `PassFailJFrame`.
> 
> As in #21145, the generated javadoc [PassFailJFrame.html](https://cr.openjdk.org/~aivanov/PassFailJFrame/api/PassFailJFrame.html) could be easier to read and review.
> 
> The current version of the generated docs contains changes from #21145 and this PR. The PRs can be integrated independently.

Alexey Ivanov has updated the pull request incrementally with one additional commit since the last revision:

  Amend: and handles timeout.

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/21162/files
  - new: https://git.openjdk.org/jdk/pull/21162/files/cbb1464a..6ba944d1

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21162&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21162&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/21162.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21162/head:pull/21162

PR: https://git.openjdk.org/jdk/pull/21162