[code-reflection] Integrated: Hat view simplification of types

[Gary Frost]

More experiments using ifaces for vector/virtex/matrices

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Commit messages:
 - common pool processing
 - towards common pools
 - towards common pools
 - don't use idx()
 - replace indices with instances

Changes: https://git.openjdk.org/babylon/pull/671/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=671&range=00
  Stats: 582 lines in 12 files changed: 114 ins; 321 del; 147 mod
  Patch: https://git.openjdk.org/babylon/pull/671.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/671/head:pull/671

PR: https://git.openjdk.org/babylon/pull/671