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/elite/bootstrap/less/alerts.less

@@ -0,0 +1,73 @@
+//
+// Alerts
+// --------------------------------------------------
+
+
+// Base styles
+// -------------------------
+
+.alert {
+  padding: @alert-padding;
+  margin-bottom: @line-height-computed;
+  border: 1px solid transparent;
+  border-radius: @alert-border-radius;
+
+  // Headings for larger alerts
+  h4 {
+    margin-top: 0;
+    // Specified for the h4 to prevent conflicts of changing @headings-color
+    color: inherit;
+  }
+
+  // Provide class for links that match alerts
+  .alert-link {
+    font-weight: @alert-link-font-weight;
+  }
+
+  // Improve alignment and spacing of inner content
+  > p,
+  > ul {
+    margin-bottom: 0;
+  }
+
+  > p + p {
+    margin-top: 5px;
+  }
+}
+
+// Dismissible alerts
+//
+// Expand the right padding and account for the close button's positioning.
+
+.alert-dismissable, // The misspelled .alert-dismissable was deprecated in 3.2.0.
+.alert-dismissible {
+  padding-right: (@alert-padding + 20);
+
+  // Adjust close link position
+  .close {
+    position: relative;
+    top: -2px;
+    right: -21px;
+    color: inherit;
+  }
+}
+
+// Alternate styles
+//
+// Generate contextual modifier classes for colorizing the alert.
+
+.alert-success {
+  .alert-variant(@alert-success-bg; @alert-success-border; @alert-success-text);
+}
+
+.alert-info {
+  .alert-variant(@alert-info-bg; @alert-info-border; @alert-info-text);
+}
+
+.alert-warning {
+  .alert-variant(@alert-warning-bg; @alert-warning-border; @alert-warning-text);
+}
+
+.alert-danger {
+  .alert-variant(@alert-danger-bg; @alert-danger-border; @alert-danger-text);
+}