RFR: 8351994: Enable Extended EVEX to REX2/REX demotion when src and dst are the same [v26]

[Srinivas Vamsi Parasa]

> Intel APX NDD instructions are encoded using EVEX encoding. The goal of this PR is to enable optimized instruction encoding for Intel APX NDD instructions when the non-destructive destination is same as the first source.
> 
> For example:
> 
> `eaddl r18, r18, r25` can be encoded as `addl r18, r25` using APX REX2 encoding
> `eaddl r2, r2, r7` can be encoded as `addl r2, r7` using non-APX legacy encoding

Srinivas Vamsi Parasa has updated the pull request incrementally with seven additional commits since the last revision:

 - complete tests refactoring to work with full_set
 - refactor demotion for full_set[4/5]
 - refactor demotion for full_set[3/5]
 - refactor demotion for full_set[2/5]
 - refactor RegRegRegImmNddInstruction demotion to work for full set as well
 - move demote loop in tests to to outer most
 - clean up gtest generation for full_set=False

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/24431/files
  - new: https://git.openjdk.org/jdk/pull/24431/files/7cfcebe9..65656aae

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=24431&range=25
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=24431&range=24-25

  Stats: 2824 lines in 3 files changed: 306 ins; 197 del; 2321 mod
  Patch: https://git.openjdk.org/jdk/pull/24431.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24431/head:pull/24431

PR: https://git.openjdk.org/jdk/pull/24431