[Security Solution][Detections] Add Endpoint Exception modal on Detection Rule page does not allow choosing OS

[marshallmain]

The "Add Endpoint Exception" modal does not mention that the exception will only be sent to endpoints of the same os family (windows, linux, or mac) as the endpoint that an alert came from, nor is there a way to choose the OS when adding an endpoint exception from the Detection Rule page (i.e. without an alert to base the exception on). Instead the OS defaults to Windows and macOS. Endpoint exceptions are OS specific so this should be clear in the UI and selectable if creating an endpoint exception from scratch.

[elasticmachine]

Pinging @elastic/siem (Team:SIEM)

[peluja1012]

This is fixed by #103404