RFR: 8255489: Unify the parsing of @lambda-proxy and @lambda-form-invokers tags in a classlist

[Calvin Cheung]

With this change, the parsing of the `@lambda-proxy` and the `@lambda-form-invokers` tags in a classlist will be performed in the same function - `ClassListParser::parse_at_tags()`.

Also removing the `:` of the `@lambda-proxy:` to be consistent with the `@lambda-form-invokers `tag.

Ran tiers 1 through 4 tests successfully.

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

Commit messages:
 - 8255489 (initial commit)

Changes: https://git.openjdk.java.net/jdk/pull/942/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=942&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8255489
  Stats: 41 lines in 8 files changed: 19 ins; 12 del; 10 mod
  Patch: https://git.openjdk.java.net/jdk/pull/942.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/942/head:pull/942

PR: https://git.openjdk.java.net/jdk/pull/942