Add max file size (http_upload) to tooltip and server info
This adds the maximum allowed file size of your server for HTTP File Upload.
Maximum file size is added to both 1:1 and group chat Send file
button's tooltip.
Maximum file size is also added in the Server Info window (and gets copied along).
XEP-0363: HTTP File Upload: Yes (urn:xmpp:http:upload:0 (max. 9.0 MiB))