Allow deliberate instances of the clippy::derivable_impls lint (#2788)

* Allow deliberate instances of the new nightly clippy::derivable_impls lint

We want our config defaults to be explicit.

Not so sure about the application defaults, but they also contain a config.

* Also allow unknown lint names

Stable doesn't know about this lint, but nightly does.

zebra-consensus/src/config.rs

@@ -14,6 +14,9 @@ pub struct Config {
     pub checkpoint_sync: bool,
 }
 
+// we like our default configs to be explicit
+#[allow(unknown_lints)]
+#[allow(clippy::derivable_impls)]
 impl Default for Config {
     fn default() -> Self {
         Self {

zebrad/src/application.rs

@@ -125,6 +125,8 @@ impl ZebradApp {
 ///
 /// By default no configuration is loaded, and the framework state is
 /// initialized to a default, empty state (no components, threads, etc).
+#[allow(unknown_lints)]
+#[allow(clippy::derivable_impls)]
 impl Default for ZebradApp {
     fn default() -> Self {
         Self {

zebrad/src/config.rs

@@ -133,6 +133,9 @@ pub struct MetricsSection {
     pub endpoint_addr: Option<SocketAddr>,
 }
 
+// we like our default configs to be explicit
+#[allow(unknown_lints)]
+#[allow(clippy::derivable_impls)]
 impl Default for MetricsSection {
     fn default() -> Self {
         Self {