Use macro per-test-file

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

tests/cases/2-ast@literals.snap

@@ -1,44 +0,0 @@
----
-source: tests/file_tests.rs
-expression: ast
-info:
-  input: "{{ if true }}\n    Hello World!\n{{ end }}"
-  context: {}
-input_file: tests/cases/literals.nomo
----
-TemplateAst {
-    root: [
-        ConditionalChain {
-            chain: [
-                Block {
-                    prev_whitespace_content: None,
-                    expression: IfConditional {
-                        expression: Literal {
-                            source: [Literal(Bool(true))]"true" (6..10),
-                            value: Bool {
-                                value: true,
-                            },
-                        },
-                    },
-                    post_whitespace_content: Some(
-                        [Whitespace]"\n    " (13..18),
-                    ),
-                },
-                ConditionalContent {
-                    content: [
-                        StaticContent(
-                            [Content]"Hello World!" (18..30),
-                        ),
-                    ],
-                },
-                Block {
-                    prev_whitespace_content: Some(
-                        [Whitespace]"\n" (30..31),
-                    ),
-                    expression: EndBlock,
-                    post_whitespace_content: None,
-                },
-            ],
-        },
-    ],
-}