RFR: [type-classes] 8375482: Basic tests for UnsignedInt

[Joe Darcy]

Add some witnesses to UnsignedInt and basic tests.

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Commit messages:
 - Add trailing newline.
 - 8375482: Basic tests for UnsignedInt

Changes: https://git.openjdk.org/valhalla/pull/1991/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1991&range=00
  Stats: 266 lines in 2 files changed: 265 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/valhalla/pull/1991.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1991/head:pull/1991

PR: https://git.openjdk.org/valhalla/pull/1991