RFR: JDK-8293364: IGV: Refactor Action in EditorTopComponent and fix minor bugs

[Tobias Holenstein]

Refactor the Actions in EditorTopComponent (com.sun.hotspot.igv.view.actions). Move Action specific code from EditorTopComponent to the corresponding Action.

# Refactoring of com.sun.hotspot.igv.view.actions and EditorTopComponent
- Created a new `ExportGraph` Action and moved corresponding functions `exportToSVG(..)` and `exportToPDF(..)` to new `ExportGraph.java`
- Moved key bindings for satellite-view (pressing S) from `EditorTopComponent` to `OverviewAction.java` 
- Moved Action specific code from `EditorTopComponent` to the corresponding `XXXAction.java`

# Fixing minor Bugs
- "Show empty blocks in control-flow graph view" is selected by default but only enabled in CFG view. 
This is distracting for the eye when we are not in CFG:
<img width="192" alt="cfg_before" src="https://user-images.githubusercontent.com/71546117/188463472-b928075f-a687-46d6-a871-35f287e943c7.png">
Now "Show empty blocks in control-flow graph view" is not selected anymore when disabled (greyed out)
<img width="192" alt="cfg_node_disable" src="https://user-images.githubusercontent.com/71546117/188463809-c998b03e-cc2f-48c1-8f5f-135edffa9c8c.png">
But still gets selected by default when enabled
<img width="197" alt="cfg_now" src="https://user-images.githubusercontent.com/71546117/188463853-33e6e7cb-b8ff-4c75-a522-63fd858b42ef.png">

- "Extract current set of selected nodes", "Hide selected nodes" and "show all nodes" were always enables, even when they didn't effect anything. 
<img width="99" alt="selection_before" src="https://user-images.githubusercontent.com/71546117/188464555-45ef06af-b247-46b0-aaa2-4c2397566f8c.png">
Now "Extract current set of selected nodes", "Hide selected nodes" are disabled (greyed out) when no nodes are selected. And "show all nodes" is disabled (greyed out) when all nodes are already visible.
<img width="91" alt="selection_now" src="https://user-images.githubusercontent.com/71546117/188464589-61310b13-ba58-45a9-b2d8-d3be0da582ab.png">

- "Reduce the difference selection" got stuck when at the last graphs in the group because it got greyed out. 
<img width="130" alt="reduce_stuck" src="https://user-images.githubusercontent.com/71546117/188465260-6fca7ca6-3e8e-4bd9-9b70-4ac19d79eff5.png">
duce the difference selection" 
Now "Reduce the difference selection" works as expected:
<img width="152" alt="reduce_now" src="https://user-images.githubusercontent.com/71546117/188465314-bce441ba-20d6-4e3d-ba4e-ff1f4a79cd9d.png">

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Commit messages:
 - Fix ReduceDiffAction stuck
 - Fix enabling of ReduceDiffAction
 - refactor OverviewAction
 - refactor HideAction, ShowAllAction and ExtractAction
 - Refactor LayoutActions
 - deselect ShowEmptyBlocksAction when disabled
 - ExportGraph.java
 - Fix satellite view
 - update SelectionModeAction
 - refactor Toolbar Actions
 - ... and 2 more: https://git.openjdk.org/jdk/compare/512fee1d...7bcf79df

Changes: https://git.openjdk.org/jdk/pull/10170/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10170&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8293364
  Stats: 1137 lines in 28 files changed: 543 ins; 443 del; 151 mod
  Patch: https://git.openjdk.org/jdk/pull/10170.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10170/head:pull/10170

PR: https://git.openjdk.org/jdk/pull/10170