Update SettingsView for macOS 26 Tahoe

[zhrispineda]

Description

This PR makes early adjustments for CodeEdit Settings with macOS 26 Tahoe due to its new design. Due to several changes in UI frameworks, workarounds that are currently used in macOS 15 or earlier have new incorrect behavior. Issues include:

• Sidebar toggle being shown again
• Top of the sidebar list having tall blank space
• Blank unusable button being shown next to the navigation title

For the toolbar, we no longer need an empty space to properly align the toolbar's navigationTitle. For the sidebar, we no longer have to rely on the stacked List workaround to fix the search bar to the top of the list. SwiftUI's updated searchable modifier has been updated to match the one in System Settings.

This beta is brand new, I will be keeping track of this to make sure it does not cause issues in future beta builds.

Checklist

• I read and understood the contributing guide as well as the code of conduct
• The issues this PR addresses are related to each other
• My changes generate no new warnings
• My code builds and runs on my machine
• My changes are all related to the related issue above
• I documented my code

Screenshots

Before, macOS 26

After, macOS 26

After, macOS 15

[thecoolwinter]

Failing test doesn't look related to this change

[austincondiff]

@allcontributors add @zhrispineda for code.

[allcontributors]

@austincondiff

I've put up a pull request to add @zhrispineda! 🎉