feat(snap): Allow overriding the inferred type

The problem today is we mutate the data according to the type so the
implicit coercion is lossy.
We need to insert logic before that happens.
The alt was to load as binary but that would be too annoying.

crates/snapbox/src/data.rs

@@ -4,8 +4,10 @@
 ///
 /// ```
 /// # use snapbox::file;
-/// file!["./test_data/bar.html"];
+/// file!["./test_data/bar.json"];
+/// file!["./test_data/bar.json": Text];
 /// file![_];
+/// file![_: Json];
 /// ```
 #[macro_export]
 macro_rules! file {
@@ -16,11 +18,23 @@ macro_rules! file {
         path.push(rel_path);
         $crate::Data::read_from(&path, None)
     }};
+    [_ : $type:ident] => {{
+        let stem = ::std::path::Path::new(::std::file!()).file_stem().unwrap();
+        let rel_path = ::std::format!("snapshots/{}-{}.txt", stem.to_str().unwrap(), line!());
+        let mut path = $crate::current_dir!();
+        path.push(rel_path);
+        $crate::Data::read_from(&path, Some($crate::DataFormat:: $type))
+    }};
     [$path:literal] => {{
         let mut path = $crate::current_dir!();
         path.push($path);
         $crate::Data::read_from(&path, None)
     }};
+    [$path:literal : $type:ident] => {{
+        let mut path = $crate::current_dir!();
+        path.push($path);
+        $crate::Data::read_from(&path, Some($crate::DataFormat:: $type))
+    }};
 }
 
 /// Test fixture, actual output, or expected result