RFR: 6974: Try to use the chromium SWT browser by default on windows

[Guru Hb]

Using SWT Chromium browser for windows .
Followed steps provided in https://www.eclipse.org/swt/faq.php#howusechromium 

With the plugin "com.make.chromium.cef.win32.win32.x86_64" inclusion in the core feature.xml makes other platform and its product definition to contain the chromium p2 site, which makes other build to have extra 56 MB of swt chromium jar which doesn't work on Eclipse 2020-06 and below. 


Note: Eclipse IDE (on Windows) add "-Dorg.eclipse.swt.browser.DefaultType=chromium" to override default browser to Chromium, Were as standalone rcp application and its jmc.ini contains this flag.

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Commit messages:
 - 6974: Try to use the chromium SWT browser by default on windows

Changes: https://git.openjdk.java.net/jmc/pull/160/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jmc&pr=160&range=00
  Issue: https://bugs.openjdk.java.net/browse/JMC-6974
  Stats: 29 lines in 6 files changed: 27 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jmc/pull/160.diff
  Fetch: git fetch https://git.openjdk.java.net/jmc pull/160/head:pull/160

PR: https://git.openjdk.java.net/jmc/pull/160