RFR: 8311085: Remove implementation detail writeTo from LocalVariable(Type) [v4]

[Chen Liang]

> `LocalVariable` and `LocalVariableType` includes `writeTo(BufWriter)`, which should be implementation details.
> 
> See https://mail.openjdk.org/pipermail/classfile-api-dev/2023-June/000381.html for context.
> 
> This patch moves the implementation to `DirectCodeBuilder`'s original use sites; the old `b.canWriteDirect` branch   is redundant, as `writeIndex`'s implementation already performs such an optimization.

Chen Liang has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains four commits:

 - Fix line ending, update corpus test
 - Share the local var writing logic in a helper class
 - oops, CorpusTest used this internal API
 - Remove implementation detail writeTo from LocalVariable(Type)

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Changes: https://git.openjdk.org/jdk/pull/14705/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14705&range=03
  Stats: 155 lines in 8 files changed: 78 ins; 69 del; 8 mod
  Patch: https://git.openjdk.org/jdk/pull/14705.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14705/head:pull/14705

PR: https://git.openjdk.org/jdk/pull/14705