Field names other than "file" seem to be broken

[gdrbyKo1]

Hi. It seems that custom field names don't work correctly with the interceptors. For example:

@UseInterceptors(
  GCloudStorageFileInterceptor('customField')
)

This will always result in the error

Can not intercept field "customField". Did you specify the correct field name in @GCloudStorageFileInterceptor('customField')?

The error originates from here:

nestjs-gcloud-storage/lib/gcloud-stroage-file.interceptor.ts

Lines 26 to 34 in 42fe011

	const file = request[fieldName];
	if (!file) {
	Logger.error(
	'GCloudStorageFileInterceptor',
	`Can not intercept field "${fieldName}". Did you specify the correct field name in @GCloudStorageFileInterceptor('${fieldName}')?`,
	);
	return;
	}

I think the line const file = request[fieldName]; is incorrect, as according to multer docs:

• Multer adds a body object and a file or files object to the request object

But the interceptor tries to access a property of the request object based on the provided fieldName parameter.
So GCloudStorageFileInterceptor('file') works, but everything else won't.

[klawdyo]

nestjs-gcloud-storage/lib/gcloud-stroage-file.interceptor.ts

Lines 20 to 30 in 42fe011

	}
	async intercept(context: ExecutionContext, next: CallHandler): Promise<Observable<any>> {
	(await this.interceptor.intercept(context, next)) as Observable<any>;
	const request = context.switchToHttp().getRequest();
	const file = request[fieldName];
	if (!file) {
	Logger.error(
	'GCloudStorageFileInterceptor',

At line 26, the correct is:

    const file = request.file;

Because multer ALWAYS inserts a key "file" on request object.