Add support for "NotResource" in MinIO IAM policy documents

[Andre-Lx-Costa]

Description

Currently, the MinIO IAM policy document schema does not support the "NotResource" element, which is used to explicitly match every resource except those specified. This will enable more flexible and secure policies.

Expected behavior:
The schema should be updated to include "NotResource" as a policy element.

Actual behavior:
The schema for MinIO IAM policy documents includes "resources" but does not support "NotResource".

Note: I am willing to contribute to this issue very soon.