Get all sets when performing LTI date synchronization.

After the issue with the names and role service URL and realizing that
the `next` link needs to be utilized to get all names and roles from the
URL, I figured I had better check the spec for the `lineitems` URL used
for set date synchronization to see if it works the same, and in fact,
it does.  See https://www.imsglobal.org/spec/lti-ags/v2p0#container-request-filters.
So this makes sure that all sets are obtained from the `lineitems` URL
in the same way.

In testing this with Canvas, it turns out that Canvas only sends 10 sets
at once.  So if a course has more than 10 sets, then only 10 sets will
be retrieved from the lineitems URL in the first request.  Note that
date synchronization will not necessarily fail though, as in the next
phase of the job queue task, requests are sent to the individual
lineitem URLs for the sets if the data was not received from the
lineitems URL for the set assuming that the lineitem URL for the set has
been obtained (webwork will have it if content item selection was used,
or if a user has entered the set directly from the LMS).  However, this
results in extra network communication that is unnecessary.

Author: drgrice1

lib/Mojolicious/WeBWorK/Tasks/LTISetDateSync.pm

@@ -52,25 +52,37 @@ async sub synchronizeSetDates ($job, $setIDs, $syncToLMS) {
 
 	my $ua = Mojo::UserAgent->new;
 
-	my $lineitemsRequest =
-		await $ua->get_p($lineitemsURL, { Authorization => "$accessToken->{token_type} $accessToken->{access_token}" })
-		->catch(sub ($err) {
-			return $err;
-		});
-
-	return $job->fail(
-		$job->maketext('There was an error communicating with the lineitems URL: [_1]', $lineitemsRequest))
-		unless ref $lineitemsRequest;
-
-	my $lineitemsResult = $lineitemsRequest->result;
-
-	return $job->fail($job->maketext(
-		'There was an error obtaining the current lineitems from the LMS: [_1]',
-		$lineitemsResult->message
-	))
-		unless $lineitemsResult->is_success;
+	my %lineitems;
+	while (1) {
+		my $lineitemsRequest =
+			await $ua->get_p($lineitemsURL,
+				{ Authorization => "$accessToken->{token_type} $accessToken->{access_token}" })->catch(sub ($err) {
+				return $err;
+				});
+
+		return $job->fail(
+			$job->maketext('There was an error communicating with the lineitems URL: [_1]', $lineitemsRequest))
+			unless ref $lineitemsRequest;
+
+		my $lineitemsResult = $lineitemsRequest->result;
+
+		return $job->fail($job->maketext(
+			'There was an error obtaining the current lineitems from the LMS: [_1]',
+			$lineitemsResult->message
+		))
+			unless $lineitemsResult->is_success;
+
+		for (@{ $lineitemsResult->json }) {
+			next unless defined $_->{resourceId};
+			$lineitems{ $_->{resourceId} } = $_;
+		}
 
-	my %lineitems = map { $_->{resourceId} => $_ } grep { defined $_->{resourceId} } @{ $lineitemsResult->json };
+		if ($lineitemsResult->headers->link && $lineitemsResult->headers->link =~ /<([^>]*)>;\s*rel="next"/) {
+			$lineitemsURL = $1;
+		} else {
+			last;
+		}
+	}
 
 	my @messages;