RFR: 8152293: Incomplete fraction reduction in getValueAsString() for TIFFTag.TIFF_RATIONAL, TIFFTag.TIFF_SRATIONAL

[Brian Burkhalter]

Remove from `TIFFField.getValueAsString` the rudimentary reduction in terms in the conversion of `RATIONAL` and `SRATIONAL` field values to a string. Also, add a test.

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Commit messages:
 - 8152293: Incomplete fraction reduction in getValueAsString() for TIFFTag.TIFF_RATIONAL, TIFFTag.TIFF_SRATIONAL

Changes: https://git.openjdk.org/jdk/pull/24141/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24141&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8152293
  Stats: 193 lines in 2 files changed: 170 ins; 20 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/24141.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24141/head:pull/24141

PR: https://git.openjdk.org/jdk/pull/24141