RFR: 8326524: Rename agent_common.h

[Kim Barrett]

Please review this trivial change that renames the file
test/hotspot/jtreg/vmTestbase/nsk/share/jvmti/agent_common/agent_common.h to
agent_common.hpp.

The #include updates were performed mechanically, and builds would fail if
there were mistakes.

The copyright updates were similarly performed mechanically. All but a handful
of the including files have already had their copyrights updated recently,
likely as part of JDK-8324681. The only change to the renamed file is a
copyright update, since no code changes were required.

Testing: mach5 tier1

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

Commit messages:
 - update copyrights
 - rename agent_common.h -- no copyrights

Changes: https://git.openjdk.org/jdk/pull/17970/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=17970&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8326524
  Stats: 551 lines in 547 files changed: 0 ins; 0 del; 551 mod
  Patch: https://git.openjdk.org/jdk/pull/17970.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17970/head:pull/17970

PR: https://git.openjdk.org/jdk/pull/17970