perf(standard-server): reduce payload size for batch request/response (#352)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- **Refactor**
- Enhanced batch request handling by conditionally including request
details, ensuring requests only feature necessary properties.
- **Tests**
- Updated test configurations and expectations to align with the
improved handling of request properties.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Author: unnoq

packages/standard-server/src/batch/request.test.ts

@@ -15,7 +15,7 @@ describe('toBatchRequest & parseBatchRequest', () => {
   const signal2 = AbortSignal.timeout(102)
 
   const headers1 = { 'x-custom': 'value' }
-  const headers2 = { 'x-custom': 'value' }
+  const headers2 = { }
   const headers3 = { 'x-custom': 'value' }
 
   it('method GET', () => {

packages/standard-server/src/batch/request.ts

@@ -15,10 +15,10 @@ export function toBatchRequest(options: ToBatchRequestOptions): StandardRequest
 
   const batchRequestItems = options.requests.map(request => ({
     body: request.body,
-    headers: request.headers,
-    method: request.method,
+    headers: Object.keys(request.headers).length ? request.headers : undefined,
+    method: request.method === options.method ? undefined : request.method,
     url: request.url,
-  } satisfies Omit<StandardRequest, 'signal'>))
+  } satisfies Partial<StandardRequest>))
 
   if (options.method === 'GET') {
     url.searchParams.append('batch', stringifyJSON(batchRequestItems))
@@ -48,9 +48,9 @@ export function parseBatchRequest(request: StandardRequest): StandardRequest[] {
 
   return items.map((item) => {
     return {
-      method: item.method,
+      method: item.method ?? request.method,
       url: new URL(item.url),
-      headers: item.headers,
+      headers: item.headers ?? {},
       body: item.body,
       signal: request.signal,
     } satisfies StandardRequest