Calculate Bottom Commanding header height instead of using constant

[joannaquu]

Platforms Impacted

• iOS
• visionOS
• macOS

Description of changes

Currently, BottomCommandingController's headerContentHeight is hard-coded in as a constant of 66. When the hero item's titles are one line, this is ok. However when it is multi-lined, there is not enough bottom padding. Update it so that headerContentHeight is calculated using systemLayoutSizeFitting.

Binary change

Total increase: 6,072 bytes
Total decrease: 0 bytes

File	Before	After	Delta
Total	31,087,872 bytes	31,093,944 bytes	⚠️ 6,072 bytes

Full breakdown

File	Before	After	Delta
BottomCommandingController.o	837,944 bytes	840,832 bytes	⚠️ 2,888 bytes
__.SYMDEF	4,813,352 bytes	4,815,168 bytes	⚠️ 1,816 bytes
FocusRingView.o	837,864 bytes	839,232 bytes	⚠️ 1,368 bytes

Verification

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)

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