Add support to run on Kubernetes, add Helm chart

See relevant README.md for more details.

kubernetes/templates/service.yaml

@@ -0,0 +1,16 @@
+apiVersion: v1
+kind: Service
+metadata:
+  name: {{ template "invidious.fullname" . }}
+  labels:
+    app: {{ template "invidious.name" . }}
+    chart: {{ .Chart.Name }}
+    release: {{ .Release.Name }}
+spec:
+  ports:
+  - name: http
+    port: 3000
+    targetPort: 3000
+  selector:
+    app: {{ template "invidious.name" . }}
+    release: {{ .Release.Name }}