Use macro per-test-file

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

tests/cases/literals.3-instructions.snap

@@ -0,0 +1,54 @@
+---
+source: tests/file_tests.rs
+expression: emit
+info:
+  input: "{{ if true }}\n    Hello World!\n{{ end }}"
+  context: {}
+---
+VMInstructions {
+    labels: {
+        LabelSlot {
+            index: 0,
+        }: 7,
+        LabelSlot {
+            index: 2,
+        }: 7,
+    },
+    instructions: [
+        LoadLiteralToSlot {
+            source: [Literal(Bool(true))]"true" (6..10),
+            value: Bool {
+                value: true,
+            },
+            slot: VariableSlot {
+                index: 1,
+            },
+        },
+        JumpIfNotTrue {
+            emit_slot: VariableSlot {
+                index: 1,
+            },
+            jump: LabelSlot {
+                index: 2,
+            },
+        },
+        AppendContent {
+            content: "\n    " (13..18),
+        },
+        AppendContent {
+            content: "Hello World!" (18..30),
+        },
+        AppendContent {
+            content: "\n" (30..31),
+        },
+        Jump {
+            jump: LabelSlot {
+                index: 0,
+            },
+        },
+        AppendContent {
+            content: "\n    " (13..18),
+        },
+        NoOp,
+    ],
+}