RFR: 8319999: Refactor MetaspaceShared::use_full_module_graph()

[Ioi Lam]

This is another step of moving CDS config management into cdsConfig.hpp:

The function `MetaspaceShared::use_full_module_graph()` is split into two:
- `CDSConfig::is_dumping_full_module_graph()`
- `CDSConfig::is_loading_full_module_graph()`

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Commit messages:
 - 8319999: Refactor MetaspaceShared::use_full_module_graph()

Changes: https://git.openjdk.org/jdk/pull/16646/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16646&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8319999
  Stats: 143 lines in 15 files changed: 69 ins; 41 del; 33 mod
  Patch: https://git.openjdk.org/jdk/pull/16646.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16646/head:pull/16646

PR: https://git.openjdk.org/jdk/pull/16646