Fix NavigationBar's title view constraints

[laminesm]

Platforms Impacted

• iOS
• macOS

Description of changes

There has been an issue where the two line title view would not fit in our navigation bar (#1883). It turns out that the constraints of the title view were not set to fit the navigation bar (which is how Apple handles the native title view).
Changes:

• Margins calculations were adjusted to give proper bottom insets to the title view
• Lowered the priority of the height constraint on the TwoLineTitleView, so that autolayout can dynamically adjust it vertically in the nav bar
• Added a bottom constraint to the titleView

Binary change

Total increase: 1,512 bytes
Total decrease: -488 bytes

File	Before	After	Delta
Total	31,330,440 bytes	31,331,464 bytes	⚠️ 1,024 bytes

Full breakdown

File	Before	After	Delta
NavigationBar.o	549,336 bytes	550,848 bytes	⚠️ 1,512 bytes
FocusRingView.o	818,960 bytes	818,888 bytes	🎉 -72 bytes
__.SYMDEF	4,826,776 bytes	4,826,360 bytes	🎉 -416 bytes

Verification

Tested fix on pro, pro max, and iPad devices on the fluent demo app.

Visual Verification

Before	After

Pull request checklist

This PR has considered:

• Light and Dark appearances
• iOS supported versions (all major versions greater than or equal current target deployment version)
• VoiceOver and Keyboard Accessibility
• Internationalization and Right to Left layouts
• Different resolutions (1x, 2x, 3x)
• Size classes and window sizes (iPhone vs iPad, notched devices, multitasking, different window sizes, etc)
• iPad Pointer interaction
• SwiftUI consumption (validation or new demo scenarios needed)
• Objective-C exposure (provide it only if needed)