Refactor HuskContext

- Provide a way to initialize a `HuskContext` without determine the
  signing key. This saves startup time for commands which do not need
  the signing key.

src/types/husk_context.rs

@@ -36,8 +36,17 @@ pub struct HuskContext<'hc> {
 
 impl<'hc> HuskContext<'hc> {
 
-    /// Create a new HuskContext instance.
     pub fn new(config: &HuskConfig) -> anyhow::Result<HuskContext<'hc>> {
+        Self::create(config, true)
+    }
+
+    /// Create a new HuskContext without determine the signing key
+    pub fn without_signkey(config: &HuskConfig) -> anyhow::Result<HuskContext<'hc>> {
+        Self::create(config, false)
+    }
+
+    /// Create a new HuskContext instance.
+    pub fn create(config: &HuskConfig, with_signkey: bool) -> anyhow::Result<HuskContext<'hc>> {
 
         let sequoia_home = Home::new(PathBuf::from(&config.sequoia_home))?;
         let cert_store_base = sequoia_home.data_dir(sequoia_directories::Component::CertD);
@@ -48,16 +57,20 @@ impl<'hc> HuskContext<'hc> {
         let local_trust_root = crypto::get_local_trust_root(&cert_store)?;
         let introducers = crypto::get_introducers(&cert_store, &policy, local_trust_root.fingerprint());
 
-        let signing_key = match crypto::get_signing_key(sequoia_home, &cert_store, &policy, &local_trust_root) {
+        let signing_key = if with_signkey {
-            Ok(Some(cert)) => Some(cert),
+            match crypto::get_signing_key(sequoia_home, &cert_store, &policy, &local_trust_root) {
-            Ok(None) => {
+                Ok(Some(cert)) => Some(cert),
-                log::warn!("No signing key found");
+                Ok(None) => {
-                None
+                    log::warn!("No signing key found");
-            },
+                    None
-            Err(e) => {
+                },
-                log::error!("Error while fetching signing key: {}", e);
+                Err(e) => {
-                None
+                    log::error!("Error while fetching signing key: {}", e);
+                    None
+                }
             }
+        } else {
+            None
         };
 
         Ok(HuskContext {