RFR: 6946: There should be an option to build the agent in the build script [v12]

[Miroslav Wengner]

> https://bugs.openjdk.java.net/browse/JMC-6946
> added: 
> - build.sh --packageAgent
> - build.sh --runAgentExample

Miroslav Wengner has updated the pull request incrementally with one additional commit since the last revision:

  6946: add agent converter example and precoditions checks ordering

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Changes:
  - all: https://git.openjdk.java.net/jmc/pull/183/files
  - new: https://git.openjdk.java.net/jmc/pull/183/files/45d494ad..e47c9dd6

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jmc&pr=183&range=11
 - incr: https://webrevs.openjdk.java.net/?repo=jmc&pr=183&range=10-11

  Stats: 15 lines in 1 file changed: 6 ins; 4 del; 5 mod
  Patch: https://git.openjdk.java.net/jmc/pull/183.diff
  Fetch: git fetch https://git.openjdk.java.net/jmc pull/183/head:pull/183

PR: https://git.openjdk.java.net/jmc/pull/183