RFR: 7006: CoreLibs: Review TPL info in all archives

[Guru Hb]

1. Updated Licenses.txt with BSD attribute + third party readme with correct attribute. 
2. Re-structured "writer" with its "test" as a separate module in "tests" 
3. Added missing Copyright attributes in some of the "java source files"

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Commit messages:
 - 7006: CoreLibs: Review TPL info in all archives

Changes: https://git.openjdk.java.net/jmc/pull/294/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jmc&pr=294&range=00
  Issue: https://bugs.openjdk.java.net/browse/JMC-7006
  Stats: 893 lines in 37 files changed: 588 ins; 247 del; 58 mod
  Patch: https://git.openjdk.java.net/jmc/pull/294.diff
  Fetch: git fetch https://git.openjdk.java.net/jmc pull/294/head:pull/294

PR: https://git.openjdk.java.net/jmc/pull/294