Create a tool to gauge the size of site or space XML backup

We tell our customers that XML backup is unreliable because it is resource intensive.

We also tell them that only XML backup less than 2 GB is supported - this can be seen when one visits the Confluence Admin page for creating site XML backup. But there is no way for them to know how big their XML backup size is until they actually perform the backup themselves.

To allow them sufficient time to manage their data, we should create a tool to measure how large is the site or space xml backup.

This will save them and us from unnecessary pain when the XML backup size has grown too large.