RFR: 8174222: LambdaMetafactory: validate inputs and improve documentation

[Dan Smith]

Standardizes and better specifies the errors thrown by LambdaMetafactory, including for inputs that would not be generated by javac.

Does some renaming of core parameters/fields to better reflect their purpose.

In the implementation, stops using ACC_BRIDGE for any methods, which is not a good fit for what these methods do (they don't delegate to each other, but all invoke the same implementation method).

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Commit messages:
 - Remove use of ACC_BRIDGE
 - Comment out failing test cases, will fix separately
 - Fixes from merge
 - Merge branch 'master' into 8174222
 - 8174222: LambdaMetafactory: validate inputs and improve documentation

Changes: https://git.openjdk.java.net/jdk/pull/4346/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4346&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8174222
  Stats: 726 lines in 4 files changed: 397 ins; 33 del; 296 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4346.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4346/head:pull/4346

PR: https://git.openjdk.java.net/jdk/pull/4346