Support object for `Policy` `policy` property

[nesl247]

When creating a Policy the policy property should support an object instead of just a string.

[shaidar]

Just checking in on this to see if there are any updates on it.

[dmattia]

How I'm doing this:

// Construct the policy document
const policyDoc = pulumi.output(
  vault.getPolicyDocument(
    {
      rules: permissions.permissions,
    },
    opts,
  ),
);

// Create the policy in Vault
const policy = new vault.Policy(
  `${name}-policy`,
  {
    name: pulumi.interpolate`${permissions.roleName}-policy`,
    policy: policyDoc.apply(({ hcl }) => hcl),
  },
   opts,
);