SharePoint Online Add Site Collection administrator to all Sites using PowerShell

Its a simple straight forward PowerShell script for adding a new user as site Collection administrator to all available SharePoint Online sites

It is easy to add a Site collection administrator to a single site from portal itself, but in my case I have more than 100+ sites in our tenant and there is a new resource joined in our team to who needs access to start his work. So PowerShell script makes life easier.