Open the linkNode inspector when pressing Ctrl+K on a link node

* Introduced MWLinkAction which opens the right link inspector
  based on what is selected.
* Added MWLinkInspectorTool overriding core's 'link' tool that
  executes MWLinkAction
* Removed MWLinkNodeInspectorTool and linkNode command,
  they're unneeded now

Bug: 72150
Change-Id: I03bd6ab1f67f31a6e6cb717cf4298e80e64637b7
Merge "Open the linkNode inspector when pressing Ctrl+K on a link node"