RFR: 6689: Export (and print?) the flame graph

[Kangcheng Xu]

This implements [JMC-6689: Export (and print?) the flame graph](https://bugs.openjdk.java.net/browse/JMC-6689)

Two actions were added to Flame View's menu bar, each for
- saving the current flame graph to the local file system as a `.jpg` or `.png` file
- sending the current flame graph to a printer (or to a `.pdf` file)

Please let me know your thoughts. Thank you very much!

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Commits:
 - 5c6b70c3: Ignored CancellationException. Fixed formatting
 - 08938bfb: Externalized ui strings
 - c67059ee: Disabled exporting actions before ready
 - 3395a67c: Fix spotless formating
 - 4e587e08: Set proper icons for new actions. Remove test console.
 - ecfdc2ce: Fix spotless formating
 - 51ce9a19: Implemented "Save sa..." and "Print" actions

Changes: https://git.openjdk.java.net/jmc/pull/56/files
 Webrev: https://webrevs.openjdk.java.net/jmc/56/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JMC-6689
  Stats: 222 lines in 6 files changed: 222 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jmc/pull/56.diff
  Fetch: git fetch https://git.openjdk.java.net/jmc pull/56/head:pull/56

PR: https://git.openjdk.java.net/jmc/pull/56