fix: markdown upload asset domain url to ctfassets.net []

[cezarsmpio]

We want to guarantee that new asset uploads will use ctfassets.net as a domain instead of contentful.com

[cezarsmpio]

We guarantee that the domain for new assets is ctfassets.net

[Stupidism]

@cezarsmpio Looks like hostname-transformer is a private npm package:

npm install @contentful/default-field-editors

npm ERR! code E404
npm ERR! 404 Not Found - GET https://registry.npmjs.org/@contentful%2fhostname-transformer - Not found
npm ERR! 404
npm ERR! 404  '@contentful/hostname-transformer@^1.4.10' is not in the npm registry.
npm ERR! 404 You should bug the author to publish it (or use the name yourself!)
npm ERR! 404 It was specified as a dependency of '@contentful/field-editor-markdown'
npm ERR! 404
npm ERR! 404 Note that you can also install from a
npm ERR! 404 tarball, folder, http url, or git url.