RFR: 7903053: Open in browser button [v2]

[Dmitry Bessonov]

> Adding a button in the Files navigation panel to allow launching external browser or other associated app to display the selected file (.html or .java etc.)
> 
> If either `java.awt.Desktop` or `Desktop.Action.BROWSE` action is not supported the button is disabled.
> 
> If `Desktop.getDesktop().browse(selected file)` call throws an exception, the exception with its stacktrace is shown in an error dialog.

Dmitry Bessonov has updated the pull request incrementally with one additional commit since the last revision:

  7903053: Open in browser button

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

Changes:
  - all: https://git.openjdk.java.net/jtharness/pull/16/files
  - new: https://git.openjdk.java.net/jtharness/pull/16/files/445d465f..56a469e6

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jtharness&pr=16&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jtharness&pr=16&range=00-01

  Stats: 4 lines in 2 files changed: 0 ins; 2 del; 2 mod
  Patch: https://git.openjdk.java.net/jtharness/pull/16.diff
  Fetch: git fetch https://git.openjdk.java.net/jtharness pull/16/head:pull/16

PR: https://git.openjdk.java.net/jtharness/pull/16