RFR: 8293293: Move archive heap loading code out of heapShared.cpp [v2]

[Ioi Lam]

> I moved all code related to loading the archive heap regions into a new file, archiveHeapLoader.cpp.
> 
> A diff of the new archiveHeapLoader.cpp and the old heapShared.cpp shows that the moved code is identical, except for the change of `HeapShared::` to `ArchiveHeapLoader::`.
> 
> I also removed unnecessary entries in JVM_EXCLUDE_FILES that are already covered by the `cds/` pattern.

Ioi Lam has updated the pull request incrementally with one additional commit since the last revision:

  Cleaned up header files

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/10138/files
  - new: https://git.openjdk.org/jdk/pull/10138/files/35c14e8d..7acf47bf

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=10138&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=10138&range=00-01

  Stats: 60 lines in 8 files changed: 7 ins; 49 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/10138.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10138/head:pull/10138

PR: https://git.openjdk.org/jdk/pull/10138