RFR: 8311085: Remove implementation detail writeTo from LocalVariable(Type) [v2]

[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 incrementally with one additional commit since the last revision:

  Share the local var writing logic in a helper class

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/14705/files
  - new: https://git.openjdk.org/jdk/pull/14705/files/544cde06..7d9a87e2

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=14705&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=14705&range=00-01

  Stats: 90 lines in 3 files changed: 58 ins; 24 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