Please review this enhancement which adds a hidden `jlink` option 
`--sha-overrides` that can be used to provide alternative hash sums for files 
in an image. Please see the bug for use-cases as to why this is needed. This 
patch allows for the `--sha-overrides` option to be either specified multiple 
times or separated by a comma to list multiple hash sum overrides. 
Alternatively when starting with the `@` character the override options come 
from a file. The format is the same: `<module>|<file-path>|<sha>` triplets, 
either on the command line or in a file (one per line).

The added, linux only, test uses `objcopy` to fully strip `libjvm.so` of its 
symbols with the assumption that this would change the hash sum of the 
resulting file. Then, a link from the run-time image is being attempted with 
the added option `--sha-overrides=java.base|lib/server/libjvm.so|<new-sha-sum>` 
and verifies the link succeeds.

Having something like that is useful when it gets combined with e.g. 
`--save-jlink-arg-files` to produce a `jlink` which works out of the box on say 
JDK builds that modify binaries due to some debug symbols handling outside the 
JDK builds' control. 

While using `--ignore-modified-runtime` is an option that is sub-optimal as 
that would spit out many warnings in the RPM build case, where the user 
wouldn't control that RPM build to begin with.

Testing:
- [ ] GHA
- [x] Some manual tests together with 
[JDK-8352692](https://bugs.openjdk.org/browse/JDK-8352692) on some JEP 493 
enabled builds.
- [x] `jlink` jtreg tests.

Thoughts?

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

Commit messages:
 - 8352689: Allow for hash sum overrides when linking from the run-time image

Changes: https://git.openjdk.org/jdk/pull/24190/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24190&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8352689
  Stats: 245 lines in 7 files changed: 228 ins; 2 del; 15 mod
  Patch: https://git.openjdk.org/jdk/pull/24190.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24190/head:pull/24190

PR: https://git.openjdk.org/jdk/pull/24190

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