[foreign-jextract] RFR: 8246341: jextract should generate Cpointer utilities class

[Athijegannathan Sundararajan]

Added Cpointer utilities class to deal with pointer values from C code.

-------------

Commit messages:
 - 8246341: jextract should generate Cpointer utilities class

Changes: https://git.openjdk.java.net/panama-foreign/pull/191/files
 Webrev: https://webrevs.openjdk.java.net/panama-foreign/191/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8246341
  Stats: 167 lines in 5 files changed: 165 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/191.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/191/head:pull/191

PR: https://git.openjdk.java.net/panama-foreign/pull/191