[XCUITests] Test cleanup

[joannaquu]

Platforms Impacted

• iOS
• macOS

Description of changes

Binary change:

File	Before	After	Delta
libFluentUI.a	28,828,696 bytes	28,828,696 bytes	0 bytes

This PR does some final cleanup for XCUITests. It updates BaseTest to remain on the control page if it starts on the correct page and fixes all the small whitespace mistakes/syntax differences (use of both XCTAssertTrue and XCTAssert) that I've noticed. It also renames the test for AvatarView to AvatarViewTest.

Verification

No visual changes, pr checks all pass.

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)