RFR: CODETOOLS-7903090: Merge othervm and agentvm classes; eliminate raw types

[Jonathan Gibbons]

Please review some moderately simple changes to update the code used in test VMs, hitherto constrained to use JDK 1.2 or 1.5.

As well as eliminating raw types, the code is converted to use standard Collection classes instead of the old Dictionary and Vector.

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Commit messages:
 - basic updates, including converting to Collections (Map, List)
 - CODETOOLS-7903090: Merge othervm and agentvm classes; eliminate raw types

Changes: https://git.openjdk.java.net/jtreg/pull/49/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jtreg&pr=49&range=00
  Issue: https://bugs.openjdk.java.net/browse/CODETOOLS-7903090
  Stats: 114 lines in 5 files changed: 2 ins; 46 del; 66 mod
  Patch: https://git.openjdk.java.net/jtreg/pull/49.diff
  Fetch: git fetch https://git.openjdk.java.net/jtreg pull/49/head:pull/49

PR: https://git.openjdk.java.net/jtreg/pull/49