frontend: Add OBSSourceView widget

[Warchamp7]

Description

Creates a new widget for displaying an OBS source preview.

Note

PR is currently a draft as it still contains logging and testing code. Widget also needs to be tested in other contexts.

Motivation and Context

This is a wrapper around the existing OBSQTDisplay which comes without batteries and some assembly required. This bundles the necessary setup and callbacks for OBSQTDisplay in an easier to use widget.

How Has This Been Tested?

Replaced the preview of the Filters window with an OBSSourceView widget, as well as adding an additional one to the sidebar.

Types of changes

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

Checklist:

• My code has been run through clang-format.
• I have read the contributing document.
• My code is not on the master branch.
• The code has been tested.
• All commit messages are properly formatted and commits squashed where appropriate.
• I have included updates to all appropriate documentation.