RFR: 8333749: Consolidate ConstantDesc conversion in java.base [v2]

[Chen Liang]

> In java.base, especially in bytecode generators, we have many different methods converting known valid Class and MethodType into ClassDesc and MethodTypeDesc. These conversions should be consolidated into the same utility method for the ease of future maintenance.

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

  mt -> md (desc)

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/19585/files
  - new: https://git.openjdk.org/jdk/pull/19585/files/cb4f6d13..3e28306f

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=19585&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=19585&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/19585.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19585/head:pull/19585

PR: https://git.openjdk.org/jdk/pull/19585