RFR: 8370800: Downgrade cant.attach.type.annotations diagnostics to warnings [v4]

[Liam Miller-Cushon]

> Hi, please consider this fix for [JDK-8370800: Downgrade cant.attach.type.annotations diagnostics to warnings](https://bugs.openjdk.org/browse/JDK-8370800).
> 
> As discussed in the, this reduces the compatibility impact of these diagnostics for builds that deliberately omit transitive annotation dependencies, for example if they are only referenced through javadoc `@link` tags, or by frameworks that conditionally load the classes.
> 
> The PR changes the existing error diagnostic to an unconditional warning. Another alternative would be to make it an optional xlint diagnostic, perhaps as part of `-Xlint:classfile`, or as another category.

Liam Miller-Cushon has updated the pull request incrementally with five additional commits since the last revision:

 - Remove .swp file
 - Update tests
 - Handle completing multiple type annotations attributes on the same symbol
 - Defer attaching type annotations to completion
 - complete

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/28018/files
  - new: https://git.openjdk.org/jdk/pull/28018/files/c65a7ac5..2781df57

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=28018&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=28018&range=02-03

  Stats: 127 lines in 4 files changed: 108 ins; 4 del; 15 mod
  Patch: https://git.openjdk.org/jdk/pull/28018.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28018/head:pull/28018

PR: https://git.openjdk.org/jdk/pull/28018