RFR: 8338544: Dedicated Array class descriptor implementation [v3]

[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.

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

  mlchung suggestions: elementType, improve utility methods

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/20665/files
  - new: https://git.openjdk.org/jdk/pull/20665/files/a1d14186..f6964d1a

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=20665&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=20665&range=01-02

  Stats: 32 lines in 2 files changed: 9 ins; 4 del; 19 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