Add test for multiple interpolations

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

tests/cases/3-instructions@multiple.snap

@@ -0,0 +1,38 @@
+---
+source: tests/file_tests.rs
+expression: emit
+input_file: tests/cases/multiple.temple
+---
+[
+    AppendContent {
+        content: "Hi there! My name is",
+    },
+    AppendContent {
+        content: " ",
+    },
+    LoadFromContextToSlot {
+        name: "name",
+        slot: VariableSlot {
+            index: 0,
+        },
+    },
+    EmitFromSlot {
+        slot: VariableSlot {
+            index: 0,
+        },
+    },
+    AppendContent {
+        content: " ",
+    },
+    LoadFromContextToSlot {
+        name: "lastname",
+        slot: VariableSlot {
+            index: 1,
+        },
+    },
+    EmitFromSlot {
+        slot: VariableSlot {
+            index: 1,
+        },
+    },
+]