RFR: 8237360: Add tests that test binding recipe generation directly

[Jorn Vernee]

This is a redo of the previous PR: https://github.com/openjdk/panama-foreign/pull/1 which was stripped when discarding some faulty merges.

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Commits:
 - d52734bd: Add some tests for binding generators

Changes: https://git.openjdk.java.net/panama-foreign/pull/5/files
 Webrev: https://webrevs.openjdk.java.net/panama-foreign/5/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8237360
  Stats: 1218 lines in 9 files changed: 1197 ins; 0 del; 21 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/5.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/5/head:pull/5

PR: https://git.openjdk.java.net/panama-foreign/pull/5