feat(fhir-ts-codegen): support mutual recursion

Generates all types as recursive types until we can identify which types
are mutually recursive. Currently, unaware of any performance tradeoffs
from making types recursive.

packages/fhir-ts-codegen/lib/index.ts

@@ -134,10 +134,17 @@ export class Generator {
     const [required, optional] = this.categorizeElementDefinitions(definitions);
     const requiredProperties = this.getProperties(required);
     const optionalProperties = this.getProperties(optional);
-    const isRecursive = definitions.some(definition => {
-      const { display } = parseType(definition);
-      return display.some(type => type === name);
-    });
+
+    /**
+     * TODO: Determine if type is mutually recursive with another type.
+     * Fine to make all types recursive for now. Unsure about perf impacts.
+     */
+    const isRecursive = true;
+    // const isRecursive =
+    //   definitions.some(definition => {
+    //     const { display } = parseType(definition);
+    //     return display.some(type => type === name);
+    //   });
 
     const runType = `t.intersection([
         t.type({