RFR: 8285150: Improve tab completion for annotations

[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.

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Commit messages:
 - 8285150: Improve tab completion for annotations

Changes: https://git.openjdk.org/jdk/pull/22840/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22840&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8285150
  Stats: 173 lines in 2 files changed: 160 ins; 0 del; 13 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