RFR: 8372155: ReleaseInfoPlugin doesn't handle input file as UTF-8 properly [v5]

[Severin Gehwolf]

> Please review this simple fix to `jlink`'s `--release-info` plugin to handle non-ASCII in vendor strings. The JDK build uses UTF-8 encoding for the produced `release` file that is being passed to `jlink` at build-time via the `--release-info` plugin. However, the plugin internally uses `java.util.Properties.load(InputStream)` API which assumes `ISO-8859-1` encoding of the input stream. The proposed fix is to use the `java.util.Prorperties.load(Reader)` API instead and pass it a `Reader` with `UTF-8` encoding (using nio API).
> 
> Testing:
> - [x] GHA
> - [x] `test/jdk/tools/jlink` tests including the new reg-test which fails prior and passes after the fix.
> 
> Thoughts?

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

  Reduce 'var' usage in test

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/28399/files
  - new: https://git.openjdk.org/jdk/pull/28399/files/65e57118..b05d1f68

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=28399&range=04
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=28399&range=03-04

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/28399.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28399/head:pull/28399

PR: https://git.openjdk.org/jdk/pull/28399