RFR: 8316969: Improve CDS module graph support for --module option [v6]

[Calvin Cheung]

> Please review this changeset for adding support for `--module` (-m) option for CDS.
> Changes in the `ModuleBootstrap.java` are needed so that the `ArchivedModuleGraph.archive` and `ArchivedBootLayer.archive` are called if the main module is specified. The module name will be stored in the ro region of the CDS archive. During runtime, the archived module name will be compared with the runtime module name. If comparison fails, the archived full module graph won't be used.
> 
> Note: this RFE is a subtask of [JDK-8266329](https://bugs.openjdk.org/browse/JDK-8266329). More subtask(s) will be created to support other options such as `--add-modules`.
> 
> Passed tiers 1 - 4 testing.

Calvin Cheung has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains ten commits:

 - Merge master
 - skip archiving full module graph is there is an incubator module
 - fix typo
 - simplify some code in modules.cpp
 - comments from Alan and Ioi; add missing @run tag in the test
 - Merge branch 'master' into improve-CDS-module-graph
 - better way to check if a module is a JDK module
 - initial review comments from Ioi
 - 8316969: Improve CDS module graph support for --module option

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Changes: https://git.openjdk.org/jdk/pull/16016/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16016&range=05
  Stats: 250 lines in 11 files changed: 236 ins; 3 del; 11 mod
  Patch: https://git.openjdk.org/jdk/pull/16016.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16016/head:pull/16016

PR: https://git.openjdk.org/jdk/pull/16016