Adds support for inspecting a hex encoded public key (#7344)

* Adds support for inspecting a hex encoded public key

This adds support for inspecting hex encoded public keys to subkey. The
command looks like:

`subkey inspect --public 0xPUBLICHEX`

* Update client/cli/src/commands/utils.rs

Co-authored-by: André Silva <123550+andresilva@users.noreply.github.com>

Co-authored-by: André Silva <123550+andresilva@users.noreply.github.com>

substrate/primitives/application-crypto/src/lib.rs

@@ -323,6 +323,14 @@ macro_rules! app_crypto_public_common {
 				)
 			}
 		}
+
+		impl<'a> $crate::TryFrom<&'a [u8]> for Public {
+			type Error = ();
+
+			fn try_from(data: &'a [u8]) -> Result<Self, Self::Error> {
+				<$public>::try_from(data).map(Into::into)
+			}
+		}
 	}
 }