Api::namespaced should work with default namespace

[clux]

Currently the kube::Config picks up on the default namespace in two ways:

• in cluster: SERVICE_DEFAULT_NS evar provided
• local dev: context.namespace.unwrap_or("default")

Which can be passed onto the kube::Client so that Api::namsepaced and Resource::namespaced can omit this if they want a controller to run in the namespace they were deployed to.

[clux]

This interplays with the planned api changes in #194.
But we could as a tempoary measure add:

• Api::default_namespaced()

Slightly harder to do Resource::default_namespaced because the that information is on the kube::Client, but that's fine. Resource is a lower level API.

[clux]

Actually, only doing one of them is awkward for the Informer init..

    let namespace = env::var("NAMESPACE").unwrap_or("default".into());
    let resource = Resource::namespaced::<Pod>(&namespace);
    let inf = Informer::new(client, ListParams::default(), resource);

We should probably move Informers and Reflectors to use Api rather than Resource, and not give it a Client. They don't need the lower-level API anyway.

[clux]

Stashed diff:

diff --git kube/src/api/typed.rs kube/src/api/typed.rs
index 16d985e5..996479ea 100644
--- kube/src/api/typed.rs
+++ kube/src/api/typed.rs
@@ -53,6 +53,16 @@ where
             phantom: PhantomData,
         }
     }
+
+    /// Namespaced resource within the configured default namespace
+    pub fn default_namespaced(client: Client) -> Self {
+        let api = Resource::namespaced::<K>(&client.default_ns);
+        Self {
+            api,
+            client,
+            phantom: PhantomData,
+        }
+    }
 }
 
 /// PUSH/PUT/POST/GET abstractions
diff --git kube/src/client/mod.rs kube/src/client/mod.rs
index 8738c0f5..280a535f 100644
--- kube/src/client/mod.rs
+++ kube/src/client/mod.rs
@@ -65,7 +65,7 @@ pub struct Status {
 #[derive(Clone)]
 pub struct Client {
     cluster_url: reqwest::Url,
-    default_ns: String,
+    pub(crate) default_ns: String,
     inner: reqwest::Client,
 }
 

[clux]

released in 0.56