Display current stopwatch in navbar (#14122)

* add notification about running stopwatch to header

* serialize seconds, duration in stopwatches api

* ajax update stopwatch

i should get my testenv working locally...

* new variant: hover dialog

* noscript compatibility

* js: live-update stopwatch time

* js live update robustness

package-lock.json

@@ -5293,6 +5293,11 @@
         "json-parse-better-errors": "^1.0.1"
       }
     },
+    "parse-ms": {
+      "version": "2.1.0",
+      "resolved": "https://registry.npmjs.org/parse-ms/-/parse-ms-2.1.0.tgz",
+      "integrity": "sha512-kHt7kzLoS9VBZfUsiKjv43mr91ea+U05EyKkEtqp7vNbHxmaVuEqN7XxeEVnGrMtYOAxGrDElSi96K7EgO1zCA=="
+    },
     "parse-node-version": {
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/parse-node-version/-/parse-node-version-1.0.1.tgz",
@@ -6702,6 +6707,14 @@
       "integrity": "sha512-s7PoyDv/II1ObgQunCbB9PdLmUcBZcnWOcxDh7O0N/UwDEsHyqkW+Qh28jW+mVuCdx7gLB0BotYI1Y6uI9iyew==",
       "optional": true
     },
+    "pretty-ms": {
+      "version": "7.0.1",
+      "resolved": "https://registry.npmjs.org/pretty-ms/-/pretty-ms-7.0.1.tgz",
+      "integrity": "sha512-973driJZvxiGOQ5ONsFhOF/DtzPMOMtgC11kCpUrPGMTgqp2q/1gwzCquocrN33is0VZ5GFHXZYMM9l6h67v2Q==",
+      "requires": {
+        "parse-ms": "^2.1.0"
+      }
+    },
     "progress": {
       "version": "2.0.3",
       "resolved": "https://registry.npmjs.org/progress/-/progress-2.0.3.tgz",