Consolidate SUI navigation functions

[carlos-zamora]

Description of the new feature

MainPage has a lot of _Navigate() functions that are all really similar.

We should consolidate them to be one big:

void _Navigate(const IInspectable& vm, BreadcrumbSubPage subPage, hstring elementToFocus = {});

Proposed technical implementation details

No response

[carlos-zamora]

AddProfile was wrong/unnecessary, so I just fixed that one.

ColorSchemesPageViewModel and ProfileViewModel still need it because they have subpages. Specifically, elementToFocus goes to the main ColorSchemes/Profiles_Base page, then gets consumed in OnNavigatedTo() there. However, the subpage navigation happens from setting VM.CurrentPage(), so when we get to the property changed handler, the original elementToFocus went out of scope and is lost.

As a workaround, I'm using these two VMs as a staging area for elementToFocus.

Actions doesn't have this problem because although it has subpages, we don't actually try to focus any of the controls in them.

That said, we've talked about refactoring the navigation code. I bet we may be able to remove these ElementToFocus members as a part of that. I suspect that if we manage the breadcrumbs and VMs properly, we may be able to just call contentFrame().Navigate() once and just include elementToFocus there like with the other pages. I'm tracking that over in #19866

from #19519 (comment)

[carlos-zamora]

qq: are these needed so that the UI updates when we get a deep-link navigation from Search?

If we unify Navigate, we may also be able to unify "Select item given the Tag that we just navigated to" as well

from #19519 (comment)

[carlos-zamora]

ah, this is one of those places where we could generalize the above when we unigy Nagivate. Instead of == addProfileTag, we wouuld simply == clickedItemTag!

from #19519 (comment)