RFR: 8300732: Whitebox functions for Metaspace test should use byte size [v4]

[Sonia Zaldana Calles]

> Hi all, 
> 
> This PR addresses [8300732](https://bugs.openjdk.org/browse/JDK-8300732) switching Whitebox Metaspace test functions to use bytes as opposed to words. 
> 
> Testing: 
> - [x] `test/hotspot/jtreg/runtime/Metaspace` tests pass. 
> 
> Thanks, 
> Sonia

Sonia Zaldana Calles has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains five commits:

 - Merge branch 'master' of github.com:openjdk/jdk into JDK-8300732
 - Feedback - updating Unit.valueOf to direct access
 - Hard coding values and adding Unit class
 - whitebox changes based on feedback. Using is_aligned and asserts
 - 8300732: Whitebox functions for Metaspace test should use byte size

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

Changes: https://git.openjdk.org/jdk/pull/20039/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20039&range=03
  Stats: 161 lines in 13 files changed: 71 ins; 0 del; 90 mod
  Patch: https://git.openjdk.org/jdk/pull/20039.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20039/head:pull/20039

PR: https://git.openjdk.org/jdk/pull/20039