fix #32 (fetch all SharePoint sites) and add MaxSites parameter

[n3rada]

Hello @dafthack 👋

Little PR to add some enhancements:

• Added MaxSites parameter to optionally limit number of unique SharePoint sites fetched
• Improved live progress output for large fetches
• Fixes Get-SharePointSiteURLs gets only the top 500 results #32
  Implements full pagination using hitsContainers.moreResultsAvailable; no longer limited to top 500 results.

You can easily try this by going to Graph Explorer, copying the JWT, and running:

Invoke-ImportTokens -AccessToken <JWT>

Then:

[n3rada]

@dafthack up?