feat: allow process from external code

Signed-off-by: kjuulh <contact@kjuulh.io>

crates/churn/wit/world.wit

@@ -1,5 +1,12 @@
 package component:churn-tasks@0.1.0;
 
+interface process {
+    resource process {
+        constructor();
+        run-process: func(inputs: list<string>) -> string;
+    }
+}
+
 interface task {
     id: func() -> string;
     should-run: func() -> bool;
@@ -8,4 +15,5 @@ interface task {
 
 world churn {
     export task;
+    import process;
 }