Problem with Repeated Use of `pipe-command` without closing popup buffer

[VisenDev]

Steps to Reproduce

• Type C-x @ and then enter some shell command such as git status and hit enter. Lem will open up a popup showing the output of the command.
• Then, enter C-x @ again while the popup is still open and start typing your command. What will happen is as soon as you enter the first key into the pipe-command prompt, lem interprets this as the signal to close the popup buffer, which then moves the cursor back into your primary text buffer, so the output of your typing will go into your text buffer rather than the prompt.

[VisenDev]

Also note that pipe-command may be renamed in the future, see #2229