RFR: 8353487: JShell LocalExecutionControl should allow decorating the execution task

[Archie Cobbs]

This PR adds the ability for subclasses of JShell's `LocalExecutionControl` to configure thread-local context in the execution thread that snippets execute in. Please see [JDK-8353487](https://bugs.openjdk.org/browse/JDK-8353487) for more details & rationale.

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Commit messages:
 - Add method LocalExecutionControl.decorateExecution().

Changes: https://git.openjdk.org/jdk/pull/24398/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24398&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8353487
  Stats: 149 lines in 2 files changed: 146 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/24398.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24398/head:pull/24398

PR: https://git.openjdk.org/jdk/pull/24398