frontend: new clipboard service and serializer introduction

[xakep8]

Description

Closes #13421

Motivation and Context

Storing an actual pointer to a source for the purposes of copying it's data or filters, rather than storing the data itself, has led to the data being wrong/missing at time of paste due to the source being changed or removed.

How Has This Been Tested?

xcodebuild -configuration RelWithDebInfo -scheme obs-studio -parallelizeTargets -destination "generic/platform=macOS,name=Any Mac"

Types of changes

• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

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

[xakep8]

@Warchamp7 The independent clipboard service and serializer currently compile locally, but have not been integrated into the UI yet. Could you please review the API design and the general direction before I proceed with the integration?