RFR: 8347471: Provide valid flags and mask in AccessFlag.Location [v11]

[Chen Liang]

> Some AccessFlag parsing methods throw IAE because a flag mask is not valid in a location. However, there is no easy way to check what flag mask bits or what flags are valid for a location. We need such APIs to check, specific to each class file format version.
> 
> Also in the investigation, it's noted that `ACC_SYNTHETIC` is incorrectly represented - it is available since release 5.0 instead of release 7. This bug is fixed together for implementation simplicity.
> 
> The new methods are all in `AccessFlag.Location`:
> - `Set<AccessFlag> flags()`
> - `int flagsMask()`
> - `Set<AccessFlag> flags(ClassFileFormatVersion)`
> - `int flagsMask(ClassFileFormatVersion)`
> 
> Also there is some simplification to `AccessFlag` itself to remove the anonymous classes, which should be more startup-friendly.
> 
> Testing: Tier 1-3

Chen Liang has updated the pull request incrementally with one additional commit since the last revision:

  Explicit imports

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Changes:
  - all: https://git.openjdk.org/jdk/pull/23095/files
  - new: https://git.openjdk.org/jdk/pull/23095/files/b651e8d8..1a22005e

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=23095&range=10
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=23095&range=09-10

  Stats: 8 lines in 1 file changed: 7 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/23095.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23095/head:pull/23095

PR: https://git.openjdk.org/jdk/pull/23095