fix fileName - undefined and fileType not present in s3 upload objects

[qxprakash]

@Murderlon while trying to reproduce and fix #5666 , #5667

I came across this bug , where uploading a file from the example code provided at examples/aws-nodejs/public/index.html
resulted in uploaded files with undefined_name in instead of fileName in the S3 key as well as no fileType present

reference -

this was because while making the request to /s3/params to get the signed URL , it parses the fileName and contentType from the request body to append it to the Key

uppy/examples/aws-nodejs/index.js

Lines 107 to 121 in f877dac

	const signOnServer = (req, res, next) => {
	// Before giving the signature to the user, you should first check is they
	// are authorized to perform that operation, and if the request is legit.
	// For the sake of simplification, we skip that check in this example.
	const Key = `${crypto.randomUUID()}-${req.body.filename}`
	const { contentType } = req.body
	getSignedUrl(
	getS3Client(),
	new PutObjectCommand({
	Bucket: process.env.COMPANION_AWS_BUCKET,
	Key,
	ContentType: contentType,
	}),

but in default case (without the customEndpoint) it's a GET request which causes this error as we're trying to parse the fileName and contentType from req body ,

uppy/packages/@uppy/aws-s3/src/index.ts

Lines 659 to 665 in f877dac

	const query = new URLSearchParams({ filename, type, ...metadata } as Record<
	string,
	string
	>)
	return this.#client.get(`s3/params?${query}`, options)
	}

After :

File uploaded with correct fileName and correct fileType