RFR: 8285150: Improve tab completion for annotations [v2]

[Jan Lahoda]

> When using types code like:
> 
> @Deprecated(
> 
> 
> and presses `<tab>`, there should be a sensible completion, but currently there is nothing. This PR proposes to add code completion for annotation attributes.

Jan Lahoda has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains six commits:

 - Fixing completion prefix behavior
 - Merge branch 'master' into JDK-8285150-dev2
 - Improving the handling of annotation attributes that are annotations and enum constants.
 - Merge branch 'master' into JDK-8285150
 - Merge branch 'master' into JDK-8285150
 - 8285150: Improve tab completion for annotations

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Changes: https://git.openjdk.org/jdk/pull/22840/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22840&range=01
  Stats: 321 lines in 4 files changed: 300 ins; 0 del; 21 mod
  Patch: https://git.openjdk.org/jdk/pull/22840.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22840/head:pull/22840

PR: https://git.openjdk.org/jdk/pull/22840