Allow themes to optionally tint windows

[austincondiff]

Description

Allow users to customize the UI by letting themes tint windows and disable the sidebar vibrancy effect if they so choose.

Adds the following settings:

• use vibrancy effect in navigator sidebar
• allow theme to tint window.

Related Issues

• closes #1259

Checklist

• [x] Add setting "Use vibrancy effect in navigator sidebar"
• [x] Add setting "Allow theme to tint window"
• [x] Add conditional backgrounds to navigator sidebar
• [ ] Add conditional backgrounds to toolbar
• [ ] Add conditional backgrounds to tab bar
• [ ] Add conditional backgrounds to path bar
• [ ] Add conditional backgrounds to status bar
• [ ] Add conditional backgrounds to debug area
• [ ] Add conditional backgrounds to inspector sidebar
• [ ] Modify outline view selection highlight when vibrancy is disabled or theme tinting is enabled
• [x] I read and understood the contributing guide as well as the code of conduct
• [x] The issues this PR addresses are related to each other
• [x] My changes generate no new warnings
• [x] My code builds and runs on my machine
• [x] My changes are all related to the related issue above
• [x] I documented my code

Screenshots

Coming soon