[code-reflection] Integrated: moved c99 codegen out of base class

[Gary Frost]

Found some C99 codegen classes in the base CodeGen class

Generally tidying up all these classes in preparation for generated C99 code from Compute layer

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Commit messages:
 - moved c99 codegen out of base class

Changes: https://git.openjdk.org/babylon/pull/736/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=736&range=00
  Stats: 417 lines in 10 files changed: 113 ins; 194 del; 110 mod
  Patch: https://git.openjdk.org/babylon/pull/736.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/736/head:pull/736

PR: https://git.openjdk.org/babylon/pull/736