feat(run): mark running configurations in the chooser, with Rerun and Stop (#1118)

A configuration with a running or debugged process gets a green dot on its icon in the Run/Debug configuration popup; its row offers Rerun and Stop in place of Run and Debug. Rerun closes the popup, Stop keeps it open.

Refs #997

src/features/run/Run.module.css

@@ -331,6 +331,22 @@
   flex: none;
   color: var(--fg-subtle);
 }
+/* A running configuration: a dot on its icon. */
+.chooserRunning {
+  position: relative;
+  display: inline-flex;
+}
+.chooserRunning::after {
+  content: "";
+  position: absolute;
+  right: -2px;
+  bottom: -1px;
+  width: 6px;
+  height: 6px;
+  border-radius: 50%;
+  background: var(--success);
+  box-shadow: 0 0 0 1px var(--bg-popup);
+}
 .chooserName {
   flex: 1;
   min-width: 0;