Avoid superfluous PUT requests for session settings upon opening a session

[schu]

If the user opens a session (/sessions/<ID>), there are number of unexpected PUT requests for the user settings:

The requests get triggered by the following reactive statements:

openmultiplechoice/resources/js/SessionView.svelte

Lines 24 to 62 in 64e55bd

	$: settingsShowSidebar = $UserSettings.session_show_sidebar;
	$: settingsExamMode = $UserSettings.session_exam_mode;
	$: settingsShuffleAnswers = $UserSettings.session_shuffle_answers;
	$: settingsShowSidebar,
	(()=> {
	axios
	.put("/api/users/me/settings", {
	session_show_sidebar: settingsShowSidebar
	})
	.then(function (response) {})
	.catch(function (error) {
	alert(error);
	});
	})();
	$: settingsExamMode,
	(()=> {
	axios
	.put("/api/users/me/settings", {
	session_exam_mode: settingsExamMode
	})
	.then(function (response) {})
	.catch(function (error) {
	alert(error);
	});
	})();
	$: settingsShuffleAnswers,
	(()=> {
	axios
	.put("/api/users/me/settings", {
	session_shuffle_answers: settingsShuffleAnswers
	})
	.then(function (response) {})
	.catch(function (error) {
	alert(error);
	});
	})();