RFR: 7903362: rename --include-macro option to be --include-constant

[Athijegannathan Sundararajan]

Option renamed. Test added for enum constant filtering.

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Commit messages:
 - 7903362: rename --include-macro option to be --include-constant

Changes: https://git.openjdk.org/jextract/pull/91/files
 Webrev: https://webrevs.openjdk.org/?repo=jextract&pr=91&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903362
  Stats: 13 lines in 5 files changed: 5 ins; 0 del; 8 mod
  Patch: https://git.openjdk.org/jextract/pull/91.diff
  Fetch: git fetch https://git.openjdk.org/jextract pull/91/head:pull/91

PR: https://git.openjdk.org/jextract/pull/91