FIX: Fixed potential crash on Mac when using stale references to deleted InputDevice objects (case ISXB-606)

[AlexTyrer]

Description

A user reported that the Editor sometimes crashed on Mac when running (their) tests in the Editor's TestRunner window

This PR addresses the root cause of the problem: stale object references were resulting in the input system accessing somewhat random memory addresses to read device state.

Some random memory address access can cause the Mac OS kernel to terminate the application instead of returning an exception to the process (this does not appear to happen on Windows).

Changes made

Added deviceIndex checks when accessing InputStateBuffers.DoubleBuffers front and back buffers to avoid reading random memory.

Testing

Local testing of the user's supplied reproduction project.

Risk

Minimal risks - these changes prevent access to essentially random memory addresses when reading device state.

Checklist

• Changelog entry added.
  • Explains the change in Changed, Fixed, Added sections.
  • For API change contains an example snippet and/or migration example.
  • JIRA ticket linked, example (case %%). If it is a private issue, just add the case ID without a link.
  • Jira port for the next release set as "Resolved".
• 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.

After merge:

• Create forward/backward port if needed. If you are blocked from creating a forward port now please add a task to ISX-1444.

[ekcoh]

Would have been nice with a test case triggering the issue but not sure whether its difficult to replicate the scenario?