Update feedback popover position when typing in a MathQuill input.

When a MathQuill input is typed in the width of the input grows.  So if
a feedback popover is open, then the popover is no longer position
correctly relative to the button.  So this updates the position of the
popover so that it stays correctly positioned as the MathQuill input
grows.

htdocs/js/MathQuill/mqeditor.js

@@ -36,6 +36,9 @@
 		if (input.classList.contains('incorrect')) answerQuill.classList.add('incorrect');
 		if (input.classList.contains('partially-correct')) answerQuill.classList.add('partially-correct');
 
+		// Find the feedback button for this input if there is one on the page.
+		const feedbackBtn = document.querySelector(`button[data-answer-label="${answerLabel}"`);
+
 		// Default options.
 		const cfgOptions = {
 			spaceBehavesLikeTab: true,
@@ -261,6 +264,9 @@
 					answerQuill.input.value = '';
 					answerQuill.latexInput.value = '';
 				}
+
+				// If the feedback popover is open, then update its position.
+				if (feedbackBtn) bootstrap.Popover.getInstance(feedbackBtn)?.update();
 			};
 
 			input.after(answerQuill);