Add Workspace and Tab controller

[erri120]

Related to #706.

• Consolidates navigation into the IWorkspaceController.
• Allows pages to change the title and icon of their tab using the ITabController.

[erri120]

2024-01-25T13:41:43.1100592Z [xUnit.net 00:00:01.09]   Finished:    NexusMods.Games.RedEngine.Tests
2024-01-25T13:41:43.1106609Z [xUnit.net 00:00:01.11]     [FATAL ERROR] System.ObjectDisposedException
2024-01-25T13:41:43.1110352Z [xUnit.net 00:00:01.11]       System.ObjectDisposedException : Cannot access a disposed object.
2024-01-25T13:41:43.1112061Z [xUnit.net 00:00:01.11]       Object name: 'Microsoft.Win32.SafeHandles.SafeWaitHandle'.
2024-01-25T13:41:43.1113025Z [xUnit.net 00:00:01.11]       Stack Trace:
2024-01-25T13:41:43.1114231Z [xUnit.net 00:00:01.11]            at System.Runtime.InteropServices.SafeHandle.DangerousAddRef(Boolean& success)
2024-01-25T13:41:43.1115697Z [xUnit.net 00:00:01.11]            at Interop.Kernel32.SetEvent(SafeWaitHandle handle)
2024-01-25T13:41:43.1116839Z [xUnit.net 00:00:01.11]            at System.Threading.EventWaitHandle.Set()
2024-01-25T13:41:43.1119795Z [xUnit.net 00:00:01.11]         /_/src/xunit.runner.utility/Extensions/MessageSinkMessageExtensions.cs(39,0): at MessageSinkMessageExtensions.Dispatch[TMessage](IMessageSinkMessage message, HashSet`1 messageTypes, MessageHandler`1 callback)
2024-01-25T13:41:44.1287611Z   Passed NexusMods.Games.FOMOD.Tests.IniParsingTests.ParseIniTest [25 ms]

This issue is once again preventing the tests from succeeding.

[github-actions]

This PR conflicts with main. You need to rebase the PR before it can be merged.

[github-actions]

This PR doesn't conflict with main anymore. It can be merged after all status checks have passed and it has been reviewed.