Build modified streamline images

The official image from streamline does not currently work for the arm64
platform. As a temporary measure, the source code and docker build scripts
have been lifted from the official images and are used to build locally.

Some additional modifications are made to reduce overall image size, these
are documented in docker/README.md

docker/streamline-src/public/fullcalendar/packages/daygrid/main.css

@@ -0,0 +1,78 @@
+/* DayGridView
+--------------------------------------------------------------------------------------------------*/
+/* day row structure */
+.fc-dayGridWeek-view .fc-content-skeleton,
+.fc-dayGridDay-view .fc-content-skeleton {
+  /* there may be week numbers in these views, so no padding-top */
+  padding-bottom: 1em;
+  /* ensure a space at bottom of cell for user selecting/clicking */
+}
+
+.fc-dayGrid-view .fc-body .fc-row {
+  min-height: 4em;
+  /* ensure that all rows are at least this tall */
+}
+
+/* a "rigid" row will take up a constant amount of height because content-skeleton is absolute */
+.fc-row.fc-rigid {
+  overflow: hidden;
+}
+
+.fc-row.fc-rigid .fc-content-skeleton {
+  position: absolute;
+  top: 0;
+  left: 0;
+  right: 0;
+}
+
+/* week and day number styling */
+.fc-day-top.fc-other-month {
+  opacity: 0.3;
+}
+
+.fc-dayGrid-view .fc-week-number,
+.fc-dayGrid-view .fc-day-number {
+  padding: 2px;
+}
+
+.fc-dayGrid-view th.fc-week-number,
+.fc-dayGrid-view th.fc-day-number {
+  padding: 0 2px;
+  /* column headers can't have as much v space */
+}
+
+.fc-ltr .fc-dayGrid-view .fc-day-top .fc-day-number {
+  float: right;
+}
+
+.fc-rtl .fc-dayGrid-view .fc-day-top .fc-day-number {
+  float: left;
+}
+
+.fc-ltr .fc-dayGrid-view .fc-day-top .fc-week-number {
+  float: left;
+  border-radius: 0 0 3px 0;
+}
+
+.fc-rtl .fc-dayGrid-view .fc-day-top .fc-week-number {
+  float: right;
+  border-radius: 0 0 0 3px;
+}
+
+.fc-dayGrid-view .fc-day-top .fc-week-number {
+  min-width: 1.5em;
+  text-align: center;
+  background-color: #f2f2f2;
+  color: #808080;
+}
+
+/* when week/day number have own column */
+.fc-dayGrid-view td.fc-week-number {
+  text-align: center;
+}
+
+.fc-dayGrid-view td.fc-week-number > * {
+  /* work around the way we do column resizing and ensure a minimum width */
+  display: inline-block;
+  min-width: 1.25em;
+}