Add signals for missing resolutions in Enhanced Boradcasting

[aleksandr-voitenko]

Description

Adds an output signal that can be emitted after the Enhanced Broadcasting config is downloaded. That signal is intended to be consumed by the paired Desktop change, which displays a custom notification explaining that Enhanced Broadcasting changed the horizontal and/or vertical canvas resolution to Twitch's selected optimal configuration.

Motivation and Context

Twitch Enhanced Broadcasting can return a go-live configuration whose top encoder resolution differs from the canvas resolution submitted by the client. This can happen when Twitch detects that a lower resolution is the optimal configuration for the user's system, for example when a user attempts to stream 1440p but Twitch selects 1080p.

Previously, this adjustment was only visible indirectly through the resulting output configuration. Desktop had no reliable, actionable signal to explain to the user why their Enhanced Broadcasting resolution changed. Twitch also returns status HTML in the config response, but those messages are not always actionable or accurate for our users, so this change avoids forwarding raw Twitch status text.

How Has This Been Tested?

Manually, Windows only.

Types of changes

• New feature (non-breaking change which adds functionality)