Add README.txt, LICENSE.txt, and NOTICES.txt to Capella tools package

For the tools package for Capella users (created in MB-50709), legal has approved using the LICENSE.txt and NOTICES.txt from the Couchbase Server Enterprise Edition (Zendesk ticket 4862).

SERVER EE LICENSE.txt — https://github.com/couchbase/product-texts/blob/master/couchbase-server/license/ee-license.txt

SERVER EE NOTICES.txt is a generated file, so not in github – build should use the same one that's used for SERVER EE build.

Also, the attached README.txt has been reviewed by Hyun-Ju Vega, Matt Carabine, and Daniel Owen. (The text in the linked document is attached as README.txt.)