RFR: JDK-8294529 : IGV: Highlight the current graphs in the Outline

[Tobias Holenstein]

# Problem
IGV marks the graph(s) of the current active `EditorTopComponent` as selected. Here is an example of a difference graph between the `Inremental Boxing Inline` and `Before CountedLoop` graphs:
<img width="280" alt="before1" src="https://user-images.githubusercontent.com/71546117/192809113-20c73d39-4627-435b-8a0d-4b36f76541b2.png">

The selection can be changed when the user selects another graph (without opening in). This is needed for example to selected graphs that the user wants to delete:
<img width="262" alt="before2" src="https://user-images.githubusercontent.com/71546117/192809411-b2203f81-5103-4b07-82aa-d4ccd9b9ae5d.png">

# Proposed Solution
Change the font of the open graph to `bold` and make the icon darker. Do the same for the folder where the graph is located. Now the user can select different graphs and still see which graphs are currently opened in the active `EditorTopComponent`. 
<img width="313" alt="new_highlighting" src="https://user-images.githubusercontent.com/71546117/192809686-73b01459-93a2-48d3-b30d-5ed19c05ec45.png">

# Implementation Details
Introduce a new `selected` variable in `FolderNode` and `GraphNode`. Whenever the currently viewed graphs change, the function `changed(InputGraphProvider lastProvider)` in `OutlineTopComponent` is called. Here we set the `FolderNode` and `GraphNode` to be (un)selected. This fires a `fireDisplayNameChange` and a `fireIconChange` which updates the text/icons.

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Commit messages:
 - JDK-8294529 : IGV: Highlight the current graphs in the Outline

Changes: https://git.openjdk.org/jdk/pull/10468/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10468&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8294529
  Stats: 65 lines in 5 files changed: 59 ins; 0 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/10468.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10468/head:pull/10468

PR: https://git.openjdk.org/jdk/pull/10468