Update OAuth grants for the specified service principal

• command: aad oauthgrant set -i|--grantId <grantId> -s|--scope <scope>
• grantId: ID of the grant to update
• scope: updated permissions scope to set on the specified grant
• requires connection to AAD Graph

The operation can be executed using the following REST call:

PATCH https://graph.windows.net/myorganization/oauth2PermissionGrants/<grantId>?api-version=1.6
content-type: application/json
authorization: Bearer eyJ0eXAiOiJKV1Qi...

{
    "scope": "<scope>"
}

Requires #160 to be done first