Feature Request: Allow mark mode key binding when search box is shown.

# Description of the new feature/enhancement

When selecting text in the middle or upper part of the screen or off screen, I tend to search for the text to navigate to it, instead of using the arrows and then selct/copy the text. Currently I have to hit Esc to hide the search box and then the mark mode key binding, somehow I don't always type that correctly and occasionally have to repeat the workflow.

Would you be open to allowing the mark mode key binding when the search box is visible to elimitate the step of having to hit Esc to hide the search box?

# Proposed technical implementation details (optional)
I did a test implementation to see what it would look like.
https://github.com/e82eric/terminal/commit/9b1b62f37613b2cc0b710fe8f78c919975cc62e3

Start by reviewing the proposed implementation commit linked in the issue and tracing how search-box input and mark-mode key bindings are handled. Confirm the behavior in Windows Terminal: the mark-mode binding should work while the search box is visible, without first pressing Esc.

Written by the indexing model from the issue text.