Project settings input actions editor saving

[jamesmcgill]

Description

-Add Save and Auto-Save buttons to the new Editor -Also required adding support for recreating the UI after domain reloads

Changes made

• Save() function added to the InputActionsEditorState
• This is called when button is pressed or on any change when Auto-Save is enabled
• InputActionsEditorState has most of it's fields changed to SerializeFields to allow reloading after domain reload (with the exception of Dictionary and SerializedObject types, these need to be recreated).
• Handle CreateGUI() after domain reload and recreate the State and UI.

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:

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