RFR: 8307508: IndirectVarHandle.isAccessModeSupported throws NPE [v2]

[Chen Liang]

> Fixes the NPE in IndirectVarHandle.isAccessModeSupported by delegating to the target var handle. In addition, simplified the MH caching in Indirect VH and removed redundant overrides (already available via var form). This was split from #13821 as suggested by Mandy Chung, which allows easy backports to release 21 if desirable.

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

  Update test/jdk/java/lang/invoke/VarHandles/IndirectVarHandleTest.java
  
  Co-authored-by: Mandy Chung <mandy.chung at oracle.com>

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Changes:
  - all: https://git.openjdk.org/jdk/pull/14409/files
  - new: https://git.openjdk.org/jdk/pull/14409/files/3b35edc1..ea7b78c8

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=14409&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=14409&range=00-01

  Stats: 3 lines in 1 file changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/14409.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14409/head:pull/14409

PR: https://git.openjdk.org/jdk/pull/14409