refactor(core): Parse Webhook request bodies on-demand (#6394)

Also,
1. Consistent CORS support ~on all three webhook types~ waiting webhooks never supported CORS. I'll fix that in another PR
2. [Fixes binary-data handling when request body is text, json, or xml](https://linear.app/n8n/issue/NODE-505/webhook-binary-data-handling-fails-for-textplain-files).
3. Reduced number of middleware that each request has to go through.
4. Removed the need to maintain webhook endpoints in the auth-exception list.
5. Skip all middlewares (apart from `compression`) on Webhook routes. 
6. move `multipart/form-data` support out of individual nodes
7. upgrade `formidable`
8. fix the filenames on binary-data in webhooks nodes
9. add unit tests and integration tests for webhook request handling, and increase test coverage

packages/cli/src/middlewares/bodyParser.ts

@@ -0,0 +1,61 @@
+import { parse as parseContentDisposition } from 'content-disposition';
+import { parse as parseContentType } from 'content-type';
+import getRawBody from 'raw-body';
+import { type RequestHandler } from 'express';
+import { jsonParse } from 'n8n-workflow';
+import config from '@/config';
+
+const payloadSizeMax = config.getEnv('endpoints.payloadSizeMax');
+export const rawBody: RequestHandler = async (req, res, next) => {
+	if ('content-type' in req.headers) {
+		const { type: contentType, parameters } = (() => {
+			try {
+				return parseContentType(req);
+			} catch {
+				return { type: undefined, parameters: undefined };
+			}
+		})();
+		req.contentType = contentType;
+		req.encoding = (parameters?.charset ?? 'utf-8').toLowerCase() as BufferEncoding;
+
+		const contentDispositionHeader = req.headers['content-disposition'];
+		if (contentDispositionHeader?.length) {
+			const {
+				type,
+				parameters: { filename },
+			} = parseContentDisposition(contentDispositionHeader);
+			req.contentDisposition = { type, filename };
+		}
+	}
+
+	req.readRawBody = async () => {
+		if (!req.rawBody) {
+			req.rawBody = await getRawBody(req, {
+				length: req.headers['content-length'],
+				limit: `${String(payloadSizeMax)}mb`,
+			});
+			req._body = true;
+		}
+	};
+
+	next();
+};
+
+export const jsonParser: RequestHandler = async (req, res, next) => {
+	await req.readRawBody();
+
+	if (Buffer.isBuffer(req.rawBody)) {
+		if (req.contentType === 'application/json') {
+			try {
+				req.body = jsonParse<unknown>(req.rawBody.toString(req.encoding));
+			} catch (error) {
+				res.status(400).send({ error: 'Failed to parse request body' });
+				return;
+			}
+		} else {
+			req.body = {};
+		}
+	}
+
+	next();
+};

packages/cli/src/middlewares/index.ts

@@ -1,2 +1,3 @@
 export * from './auth';
+export * from './bodyParser';
 export * from './cors';