Use macro per-test-file

Signed-off-by: Marcel Müller <neikos@neikos.email>

tests/cases/1-parsed@literals.snap

@@ -1,27 +0,0 @@
----
-source: tests/file_tests.rs
-expression: parsed
-info:
-  input: "{{ if true }}\n    Hello World!\n{{ end }}"
-  context: {}
-input_file: tests/cases/literals.nomo
----
-ParsedTemplate {
-    tokens: [
-        [LeftDelim]"{{" (0..2),
-        [Whitespace]" " (2..3),
-        [ConditionalIf]"if" (3..5),
-        [Whitespace]" " (5..6),
-        [Literal(Bool(true))]"true" (6..10),
-        [Whitespace]" " (10..11),
-        [RightDelim]"}}" (11..13),
-        [Whitespace]"\n    " (13..18),
-        [Content]"Hello World!" (18..30),
-        [Whitespace]"\n" (30..31),
-        [LeftDelim]"{{" (31..33),
-        [Whitespace]" " (33..34),
-        [End]"end" (34..37),
-        [Whitespace]" " (37..38),
-        [RightDelim]"}}" (38..40),
-    ],
-}