RFR: 8352689: Allow for hash sum overrides when linking from the run-time image [v3]

[Severin Gehwolf]

> 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:
> - [x] 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?

Severin Gehwolf has updated the pull request incrementally with one additional commit since the last revision:

  Remove @enablePreview from runtimeImage tests

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Changes:
  - all: https://git.openjdk.org/jdk/pull/24190/files
  - new: https://git.openjdk.org/jdk/pull/24190/files/e387bd64..dbd7fe09

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=24190&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=24190&range=01-02

  Stats: 16 lines in 16 files changed: 0 ins; 16 del; 0 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