RFR: 8338544: Dedicated Array class descriptor implementation

[Chen Liang]

@cl4es discovered that Stack Map generation in ClassFile API uses `componentType` and `arrayType` for `aaload` `aastore` instructions, which are currently quite slow. We can split out array class descriptors from class or interfaces to support faster `arrayType` and `componentType` operations.

Tentative, as I currently have no way to measure the actual impact of this patch on the startup performance; however, this made the `ClassDesc` implementations much cleaner.

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Commit messages:
 - Cleanup after merge
 - Merge branch 'master' of https://github.com/openjdk/jdk into feature/array-cd
 - Merge branch 'master' of https://github.com/openjdk/jdk into feature/array-cd
 - Compile error
 - Redundant import
 - Merge branch 'master' of https://github.com/openjdk/jdk into feature/array-cd
 - 8338544: Dedicated Array class descriptor implementation

Changes: https://git.openjdk.org/jdk/pull/20665/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20665&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8338544
  Stats: 384 lines in 11 files changed: 244 ins; 108 del; 32 mod
  Patch: https://git.openjdk.org/jdk/pull/20665.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20665/head:pull/20665

PR: https://git.openjdk.org/jdk/pull/20665