chore: update jenkins and plugins to latest lts, update gh actions, add flake, remove minikube and use kind (#974)

- update to latest jenkins lts
- update github actions
- add nix flake (experimental, build artifacts still wip)
- remove minikube and use kind for a better experience

api/v1alpha2/zz_generated.deepcopy.go

@@ -1,4 +1,3 @@
-//go:build !ignore_autogenerated
 // +build !ignore_autogenerated
 
 /*
@@ -357,6 +356,11 @@ func (in *JenkinsMaster) DeepCopyInto(out *JenkinsMaster) {
 		*out = make([]Plugin, len(*in))
 		copy(*out, *in)
 	}
+	if in.LatestPlugins != nil {
+		in, out := &in.LatestPlugins, &out.LatestPlugins
+		*out = new(bool)
+		**out = **in
+	}
 	if in.HostAliases != nil {
 		in, out := &in.HostAliases, &out.HostAliases
 		*out = make([]corev1.HostAlias, len(*in))