refactor: move file_sscv into file::sscv, rename crate feature

src/certs/file/mod.rs

@@ -0,0 +1 @@
+pub mod sscv;

src/certs/mod.rs

@@ -3,8 +3,8 @@
 pub mod fingerprint;
 pub mod verifier;
 
-#[cfg(feature = "file-sscv")]
-pub mod file_sscv;
+#[cfg(feature = "file")]
+pub mod file;
 
 #[cfg(feature = "hickory")]
 pub mod dane;