RFR: 8339576: Speed up raw bytecode processing in ClassFile API

[Chen Liang]

Currently, raw bytecode access goes through multiple wrappers, include one from ClassFile API and another ByteBuffer for merged big endian value reads. We can merge the ByteBuffer =into the ClassFile API one (RawBytecodeHelper) for safer access.

RawBytecodeHelper is also restructured so we avoid allocating it on the heap. Large `rawNext` method is now also inlined into the smaller `next` method.

Current benchmark results show this significantly speeds up `jdk.classfile.Write` and some degree of speedup for simple lambda startup. The impact on general application workloads is minuscule, but this doesn't seem to bring any regression.

Pinging @wenshao and @cl4es for review.

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Commit messages:
 - Simplify state transition logic, fix dump logical error and comment error
 - Use inlined representation for class initializer, loop initialization too costly
 - Bad assertion
 - Encapsulate RawBytecodeHelper, controlled unchecked access
 - remove benchmark
 - Inline ByteBuffer into RawBytecodeHelper, and try to make it eligible for escape analysis
 - simplify ByteBuffer improve startup performance
 - add benchmark

Changes: https://git.openjdk.org/jdk/pull/20863/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20863&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8339576
  Stats: 471 lines in 9 files changed: 196 ins; 101 del; 174 mod
  Patch: https://git.openjdk.org/jdk/pull/20863.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20863/head:pull/20863

PR: https://git.openjdk.org/jdk/pull/20863