Sets the SharePoint site admin for a given site.
The Set-CIPPSharePointSiteAdmin function sets the SharePoint site admin for a specified site by making a REST API call to the CIPP API.
Specifies whether to remove the admin permission for the current admin UPN.
PS > Set-CIPPSharePointSiteAdmin -CustomerTenantID "contoso.onmicrosoft.com" -CurrentAdminUPN "admin@contoso.com" -SiteUrl "https://contoso.sharepoint.com/sites/site1" -RemovePermission $true -AdditionalAdminUPN "admin2@contoso.com"