RFR: 8068: Move JMC 9 to JDK 17 [v2]

[Brice Dutheil]

> This PR builds atop #359 which has a number of improvement.
> * #359
> 
> It removed older platform that didn't support Java17 (see https://wiki.eclipse.org/Eclipse/Installation).
> 
> I didn't changed the agent to 17 though.

Brice Dutheil has updated the pull request incrementally with seven additional commits since the last revision:

 - Fix spotbug issue on GreyChartPanelTester
   
   Fixed STCAL_INVOKE_ON_STATIC_DATE_FORMAT_INSTANCE
 - Mention JVMKeepAlive
   
   Using a predefinied launcher does not work properly (in my setting)
 - Improve devguide
 - Update DEVGUIDE JDK instructions
 - Fix formatting
 - Fix PropertyContentBuilderTest
   
   Related to differences in events between JDK11 and later JDKs
 - Make CI use JDK 17

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

Changes:
  - all: https://git.openjdk.org/jmc/pull/482/files
  - new: https://git.openjdk.org/jmc/pull/482/files/d1b6edad..ac9aa80d

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jmc&pr=482&range=01
 - incr: https://webrevs.openjdk.org/?repo=jmc&pr=482&range=00-01

  Stats: 60 lines in 5 files changed: 37 ins; 2 del; 21 mod
  Patch: https://git.openjdk.org/jmc/pull/482.diff
  Fetch: git fetch https://git.openjdk.org/jmc.git pull/482/head:pull/482

PR: https://git.openjdk.org/jmc/pull/482