libobs: Create unique groups when duplicating scene

[Warchamp7]

Description

Updates obs_scene_duplicate to always duplicate groups within the duplicated scene.

This fixes the weird behavior of groups in Studio Mode when Duplicate Scenes is ON and Duplicate Sources is OFF (These are the default settings)

Motivation and Context

Studio mode allows users to modify a scene without the changes happening live in Program.

Since we default to Duplicate Scenes enabled and Duplicate Sources disabled, sources that are nested in a scene (or a group) still have their changes reflected immediately in program. In some cases, this is desirable behavior.

However, this has two drawbacks.

1. The size and position of a group updates based on its contents. This leads to extremely unpredictable behavior for groups with Studio Mode enabled on the default settings, as the groups size and position effectively desyncs
2. Most users don't realize that groups are scenes, and not a UI abstraction, meaning the nested scene behavior is usually confusing and undesirable

How Has This Been Tested?

Adjusted the size and position of a group as well as it's contents in normal mode and studio mode.

Tested with all combinations of Duplicate Scenes and Duplicate Sources ON and OFF

Types of changes

• Bug fix (non-breaking change which fixes an issue)

• Tweak (non-breaking change to improve existing 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.

[Warchamp7]

This PR was originally Drafted due to duplicating a scene causing any groups in it to be created as duplicates rather than references.

However since this PR, our envisioned UX around groups has changed to prefer duplication and the new add source flow actively discourages group references.

Situations where users want a collection of sources that can be referenced in multiple places and updated once should use Scenes as sources and improvements around that workflow are planned. Groups should remain as strictly an organizational tool within a particular scene.