Add structure and interface for csv dynamic node

wit/dynamic_node.wit

@@ -1,35 +1,47 @@
 package vato007:ingey;
 
-world dynamic {
-    resource row {
-        get: func(name: string) -> string;
+interface types {
+    resource csv-row {
+        columns: func() -> list<string>;
+        values: func() -> list<string>;
+        entries: func() -> list<tuple<string, string>>;
+        value: func(name: string) -> option<string>;
     }
 
-    resource reader {
+    resource csv-reader {
         columns: func() -> list<string>;
 
-        next: func() -> row;
+        next: func() -> csv-row;
         has-next: func() -> bool;
 
         // Get a row by values in one or more columns
-        query: func(values: list<tuple<string, string>>) -> row;
+        query: func(values: list<tuple<string, string>>) -> csv-row;
+
+        read-into-string: func() -> string;
+        read-into-map: func() -> read-map;
+    }
+
+    resource write-map {
+        keys: func() -> list<string>;
+        put: func(name: string, value: string);
+    }
+
+    resource csv-readers {
+        get-reader: func(name: string) -> option<csv-reader>;
+    }
+
+    resource csv-writer {
+        write-map: func(row: write-map);
+        write-row: func(row: list<tuple<string, string>>);
     }
 
     resource read-map {
         get: func(key: string) -> string;
     }
+}
 
-    resource write-map {
-        add: func(name: string, value: string);
-    }
-
-    resource readers {
-        get-reader: func(name: string) -> option<reader>;
-    }
-
-    resource writer {
-        write: func(row: write-map);
-    }
-
-    export evaluate: func(readers: readers, properties: read-map, writer: writer);
+// This will apply to csv files only for simplicity. A separate node should be created for arbitrary readers/writers
+world dynamic {
+    use types.{csv-readers, read-map, csv-writer};
+    export evaluate: func(properties: read-map, readers: csv-readers, writer: csv-writer);
 }