Allow stack owners to simulate policy on those stacks

We use spaces to govern stack permissions - ie: teams have stack permissions within spaces that we manage through custom read/write roles. And our users are also able to specify custom policy rules for their stacks (most commonly used for custom approval policies). There is no way for us to allow permissions for users to perform policy simulations on the policy they own (ie: the ones that are applied to their stack runs in their spaces). Users should be able to use the same policy debugging tools that admins use for policies being applied to their stacks.