## Summary of the Pull Request
Currently, when the user attempts to type using IME while the Search Box is focused, the input goes to the terminal instead. This is due to the fact that the `TSFInputControl` assumes it's in control whenever TermControl gets focus. So, it'll intercept IME input before the Search Box receives it. We simply need to modify `TermControl::GotFocus` to check if the SearchBox has focus. If it does, `TSFInputControl::NotifyFocusEnter` shouldn't be called.
As a small side fix, I've also disabled the terminal cursor blinking when the Search Box has focus.
Thinking a little further, if we have more features in the future that behave like search box (i.e. advanced tab switcher, or any other XAML controls that pop up) and require text input, we might need to create a sort of "AnyOtherTextControlInFocus" function to see if TSFInputControl should receive focus or not.
## PR Checklist
* [x] Closes#4434
* [x] CLA signed. If not, go over [here](https://cla.opensource.microsoft.com/microsoft/Terminal) and sign the CLA
* [x] Tests added/passed
## Validation Steps Performed
Search works as expected with IME. Composition picker appears underneath Search Box when typing IME in the Search Box. Clicking outside of the Search Box still returns control to TSFInputControl/TermControl.
Terminal Cursor blinks when it has focus, and doesn't when the Search Box has focus.
61e5917fe8