RFR: 8182025: PropertyDescriptor ignores default methods from interfaces implemented by superclasses

[Archie L. Cobbs]

The `Introspector` class was never updated to include `default` methods inherited from interfaces.

This patch attempts to fix that omission.

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Commit messages:
 - Include default methods inherited from interfaces in bean introspection.

Changes: https://git.openjdk.org/jdk/pull/13544/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13544&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8182025
  Stats: 121 lines in 2 files changed: 115 ins; 0 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/13544.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13544/head:pull/13544

PR: https://git.openjdk.org/jdk/pull/13544