remove connected disconnected state only (#3868)

* remove connected disconnected state from overseer

* foo

* split new partial

* fix

* refactor init code to not require a `OverseerHandle` when we don't have an overseer

* intermediate

* fixins

* X

* fixup

* foo

* fixup

* docs

* conditional

* Update node/service/src/lib.rs

* review by ladi

polkadot/node/overseer/overseer-gen/proc-macro/src/impl_builder.rs

@@ -130,7 +130,7 @@ pub(crate) fn impl_builder(info: &OverseerInfo) -> proc_macro2::TokenStream {
 				&mut self.handle
 			}
 			/// Obtain access to the overseer handle.
-			pub fn as_handle(&mut self) -> &#handle {
+			pub fn as_handle(&self) -> &#handle {
 				&self.handle
 			}
 		}