RFR: JDK-8304036: Use CommandLine class from shared module

[Christian Stein]

This pull request addresses the open ends left by [JDK-8236919](https://bugs.openjdk.org/browse/JDK-8236919):
- #11272

Changes:
- [x] Extend list of targeted exports of `jdk.internal.opt/jdk.internal.opt` to `jdk.compiler` and `jdk.javadoc`
- [x] Use shared `CommandLine.java` in `jdk.compiler` module
- [x] Use shared `CommandLine.java` in `jdk.javadoc` module
- [x] Remove `CommandLine.java` from `jdk.compiler` module

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Commit messages:
 - Add missing import
 - JDK-8304036: Use CommandLine class from shared module

Changes: https://git.openjdk.org/jdk/pull/12997/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12997&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8304036
  Stats: 310 lines in 6 files changed: 7 ins; 297 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/12997.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12997/head:pull/12997

PR: https://git.openjdk.org/jdk/pull/12997