Retrieve an OAuth 2.0 access token for Power Platform services.
POST https://login.microsoftonline.com/{tenant}/oauth2/v2.0/token
Content-Type: application/x-www-form-urlencoded
client_id={clientId}&
scope=https%3A%2F%2Fapi.powerplatform.com%2F.default&
client_secret={clientSecret}&
grant_type=client_credentials