FIX: Avoid jumping around Actions list due to premature asset saving (ISXB-801)

[graham-huws]

Description

Fix for ISXB-801, where editing the binding path for a newly added action's binding would cause the selection to jump to the top action instead.

Changes made

Use the opening and closing of the IMGUI dropdown window to inform the settings window of how to act.

Checklist

Before review:

• [ ] Changelog entry added.
  • Explains the change in Changed, Fixed, Added sections.
  • For API change contains an example snippet and/or migration example.
  • FogBugz ticket attached, example ([case %number%](https://issuetracker.unity3d.com/issues/...)).
  • FogBugz is marked as "Resolved" with next release version correctly set.
• [ ] Tests added/changed, if applicable.
  • Functional tests Area_CanDoX, Area_CanDoX_EvenIfYIsTheCase, Area_WhenIDoX_AndYHappens_ThisIsTheResult.
  • Performance tests.
  • Integration tests.
• [ ] Docs for new/changed API's.
  • Xmldoc cross references are set correctly.
  • Added explanation how the API works.
  • Usage code examples added.
  • The manual is updated, if needed.

During merge:

• [x] Commit message for squash-merge is prefixed with one of the list:
  • NEW: ___.
  • FIX: ___.
  • DOCS: ___.
  • CHANGE: ___.
  • RELEASE: 1.1.0-preview.3.

[stefanunity]

It fails on 2021.3 (doesn't support the UITK version of the editor nor projectwide actions afaik) with the following compilation error:

Packages/com.unity.inputsystem/InputSystem/Editor/ControlPicker/InputControlPathEditor.cs(165,13): error CS0103: The name 'InputActionsEditorSettingsProvider' does not exist in the current context

[unity-cla-assistant]

All committers have signed the CLA.