transform: move rust base64 to dedicated subdirectory

rust/src/detect/mod.rs

@@ -26,7 +26,6 @@ pub mod iprep;
 pub mod parser;
 pub mod requires;
 pub mod stream_size;
-pub mod transform_base64;
 pub mod transforms;
 pub mod uint;
 pub mod float;

rust/src/detect/transforms/mod.rs

@@ -17,6 +17,7 @@
 
 //! Module for transforms
 
+pub mod base64;
 pub mod casechange;
 pub mod compress_whitespace;
 pub mod domain;