RFR: 8307567: Avoid relocating global roots to metaspaceObjs in CDS dump

[Ioi Lam]

The functions `ArchiveBuilder::relocate_roots()` and `ArchiveBuilder::relocate_vm_classes()` relocate global roots such as `Universe::_typeArrayKlassObjs[]` and `vmClasses::_klasses[]` to point to locations inside the CDS "buffer" space.

As a result, the VM is no longer usable after CDS dumping has finished.

Previously, we tried to save some of the VM states and restore them after CDS dump has finished. See [JDK-8264735](https://bugs.openjdk.org/browse/JDK-8264735), which added functions like `FileMapInfo::clone_shared_path_table()`.

However, this is too cumbersome and doesn't cover all cases. The intention of the global root relocation is to make it easy to write the roots using `WriteClosure::do_ptr()`, which could handle only pointers into the "buffer" space. If we call `get_buffered_addr()` inside `WriteClosure::do_ptr()`, then there's no need to modify the global roots.

Notes for reviewers:

- Start with changes in `WriteClosure::do_ptr()`
- Some code in SystemDictionaryShared also needed to call `get_buffered_addr()`
- I added new function `ArchiveBuilder::write_pointer_in_buffer()` to simplify writing pointers into the CDS buffer
-  `ArchiveBuilder::relocate_roots()`, `ArchiveBuilder::relocate_vm_classes()` and `FileMapInfo::clone_shared_path_table()` are removed.
    - I am leaving `CloneDumpTimeClassTable` and `CloneDumpTimeLambdaProxyClassTable` for now. I plan to remove them in a follow up RFE after more testing.

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Commit messages:
 - added comments and assert; fixed spaces
 - 8307567: Avoid relocating global roots to metaspaceObjs in CDS dump

Changes: https://git.openjdk.org/jdk/pull/13854/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13854&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8307567
  Stats: 321 lines in 14 files changed: 135 ins; 130 del; 56 mod
  Patch: https://git.openjdk.org/jdk/pull/13854.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13854/head:pull/13854

PR: https://git.openjdk.org/jdk/pull/13854