RFR: 8319875: Add macOS implementation for jcmd System.map [v6]

[Simon Tooke]

> This is a port of #16301  to macOS.
> 
> System.map and System.dump_map are implemented using the macOS API and provide roughly the same information in the same format. Most of the heavy lifting was implemented by @tstuefe in https://github.com/openjdk/jdk/pull/16301 - this PR adds the macOS implementation and enables the common code for macOS 64 bit.
> 
> The System.map tests are also reworked to be cleaner for the three implementations.
> 
> [Sample output](https://github.com/user-attachments/files/17517412/sample.txt)

Simon Tooke has updated the pull request incrementally with one additional commit since the last revision:

  fix test for ZGC

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Changes:
  - all: https://git.openjdk.org/jdk/pull/20953/files
  - new: https://git.openjdk.org/jdk/pull/20953/files/6e368aed..8e19b687

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=20953&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=20953&range=04-05

  Stats: 3 lines in 1 file changed: 2 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/20953.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20953/head:pull/20953

PR: https://git.openjdk.org/jdk/pull/20953