UI: Add preview zoom controls

[cg2121]

Description

This adds preview zoom out and zoom in buttons next the the scaling percent label. This also adds these as actions in the scaling menu, along with a reset zoom action.

Motivation and Context

Makes the scaling UI better

How Has This Been Tested?

Zoomed in and out the preview

Types of changes

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

Checklist:

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

[Warchamp7]

This was something on my todo list for after the Preview controls were added. Will need a visual pass from myself at some point