Does what it says on the tin. This is maximal BODGE. 

`TeachingTip` doesn't provide an `Opened` event.
(microsoft/microsoft-ui-xaml#1607). But we
want to focus the renamer text box when it's opened. We can't do that
immediately, the TextBox technically isn't in the visual tree yet. We
have to wait for it to get added some time after we call IsOpen. How do
we do that reliably? Usually, for this kind of thing, we'd just use a
one-off LayoutUpdated event, as a notification that the TextBox was
added to the tree. HOWEVER:
* The _first_ time this is fired, when the box is _first_ opened,
  yeeting focus doesn't work on the first LayoutUpdated. It does work on
  the second LayoutUpdated. Okay, so we'll wait for two LayoutUpdated
  events, and focus on the second.
* On subsequent opens: We only ever get a single LayoutUpdated. Period.
  But, you can successfully focus it on that LayoutUpdated.

So, we'll keep track of how many LayoutUpdated's we've _ever_ gotten. If
we've had at least 2, then we can focus the text box.

We're also not using a ContentDialog for this, because in Xaml Islands a
text box in a ContentDialog won't receive _any_ keypresses. Fun!


## References
* microsoft/microsoft-ui-xaml#1607
* microsoft/microsoft-ui-xaml#6910
* microsoft/microsoft-ui-xaml#3257
* #9662

## PR Checklist
* [x] Will close out #12021, but that's an a11y bug that needs secondary
  validation
* [x] Closes #11322
* [x] I work here
* [x] Tests added/passed
* [n/a] Requires documentation to be updated

## Validation Steps Performed

Tested manually

Does what it says on the tin. This is maximal BODGE.

`TeachingTip` doesn't provide an `Opened` event.
(microsoft/microsoft-ui-xaml#1607). But we
want to focus the renamer text box when it's opened. We can't do that
immediately, the TextBox technically isn't in the visual tree yet. We
have to wait for it to get added some time after we call IsOpen. How do
we do that reliably? Usually, for this kind of thing, we'd just use a
one-off LayoutUpdated event, as a notification that the TextBox was
added to the tree. HOWEVER:
* The _first_ time this is fired, when the box is _first_ opened,
  yeeting focus doesn't work on the first LayoutUpdated. It does work on
  the second LayoutUpdated. Okay, so we'll wait for two LayoutUpdated
  events, and focus on the second.
* On subsequent opens: We only ever get a single LayoutUpdated. Period.
  But, you can successfully focus it on that LayoutUpdated.

So, we'll keep track of how many LayoutUpdated's we've _ever_ gotten. If
we've had at least 2, then we can focus the text box.

We're also not using a ContentDialog for this, because in Xaml Islands a
text box in a ContentDialog won't receive _any_ keypresses. Fun!

## References
* microsoft/microsoft-ui-xaml#1607
* microsoft/microsoft-ui-xaml#6910
* microsoft/microsoft-ui-xaml#3257
* #9662

## PR Checklist
* [x] Will close out #12021, but that's an a11y bug that needs secondary
  validation
* [x] Closes #11322
* [x] I work here
* [x] Tests added/passed
* [n/a] Requires documentation to be updated

## Validation Steps Performed

Tested manually

(cherry picked from commit b57fe85)
Service-Card-Id: 79978834
Service-Version: 1.13

Does what it says on the tin. This is maximal BODGE.

`TeachingTip` doesn't provide an `Opened` event.
(microsoft/microsoft-ui-xaml#1607). But we
want to focus the renamer text box when it's opened. We can't do that
immediately, the TextBox technically isn't in the visual tree yet. We
have to wait for it to get added some time after we call IsOpen. How do
we do that reliably? Usually, for this kind of thing, we'd just use a
one-off LayoutUpdated event, as a notification that the TextBox was
added to the tree. HOWEVER:
* The _first_ time this is fired, when the box is _first_ opened,
  yeeting focus doesn't work on the first LayoutUpdated. It does work on
  the second LayoutUpdated. Okay, so we'll wait for two LayoutUpdated
  events, and focus on the second.
* On subsequent opens: We only ever get a single LayoutUpdated. Period.
  But, you can successfully focus it on that LayoutUpdated.

So, we'll keep track of how many LayoutUpdated's we've _ever_ gotten. If
we've had at least 2, then we can focus the text box.

We're also not using a ContentDialog for this, because in Xaml Islands a
text box in a ContentDialog won't receive _any_ keypresses. Fun!

## References
* microsoft/microsoft-ui-xaml#1607
* microsoft/microsoft-ui-xaml#6910
* microsoft/microsoft-ui-xaml#3257
* #9662

## PR Checklist
* [x] Will close out #12021, but that's an a11y bug that needs secondary
  validation
* [x] Closes #11322
* [x] I work here
* [x] Tests added/passed
* [n/a] Requires documentation to be updated

## Validation Steps Performed

Tested manually

(cherry picked from commit b57fe85)
Service-Card-Id: 79978833
Service-Version: 1.12