Issue #3340146: Add test coverage for per-bundle export on UI, and for...

Issue #3340146: Add test coverage for per-bundle export on UI, and for per-bundle and entity specific export on CLI

Closes #3340146

css/eme.admin.css

+/**
+ * @file
+ * Admin styles for EME.
+ */
+
+.eme-horizontal-line {
+  display: flex;
+}
+
+.eme-horizontal-line::before,
+.eme-horizontal-line::after {
+  display: flex;
+  flex: 1 1 auto;
+  margin: 0 1em;
+  content: "";
+  transform: translateY(50%);
+  border-color: var(--color-divider, #888);
+  border-top: 1px solid;
+}