RFR: 8291065: Creating a VarHandle for a static field triggers class initialization

[Chen Liang]

Also fixed the bug with NPE in `IndirectVarHandle::isAccessModeSupported`.

A few implementation-detail methods in VarHandle are now documented with the implied constraints to avoid subtle problems in the future. Changed `IndirectVarHandle` to call `asDirect` lazily to accomodate the lazy VarHandle changes. Also changed VarHandleBaseTest to report the whole incorrect type of exception caught than swallow it and leaving only a message.

Current problems:
- [ ] The lazy var handle is quite slow on the first invocation.
   - As seen in the benchmark, users can first call `Lookup::ensureInitialized` to create an eager handle.
   - After that, the lazy handle has a performance on par with the regular var handle.
- [ ] The class-loading-based test is not in a unit test
   - The test frameworks don't seem to offer fine-grained control for class-loading detection or reliable unloading


Benchmark                                            Mode  Cnt       Score        Error  Units
VarHandleLazyStaticInvocation.initializedInvocation  avgt   30       0.769 ±      0.003  ns/op
VarHandleLazyStaticInvocation.lazyInvocation         avgt   30       0.767 ±      0.002  ns/op
VarHandleLazyStaticCreation.eagerInitialize            ss   10  348580.000 ± 115234.161  ns/op
VarHandleLazyStaticCreation.lazyInitialize             ss   10  961670.000 ± 154813.238  ns/op

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

Commit messages:
 - copyright year
 - Benchmarks. lazy initialize is SLOW
 - nuke meaningless overrides
 - make static field var handles lazy and fix NPE in isAccessModeSupported

Changes: https://git.openjdk.org/jdk/pull/13821/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13821&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8291065
  Stats: 509 lines in 9 files changed: 418 ins; 17 del; 74 mod
  Patch: https://git.openjdk.org/jdk/pull/13821.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13821/head:pull/13821

PR: https://git.openjdk.org/jdk/pull/13821