feat(postgresql): support WITH INHERIT FALSE on role membership grants (PostgreSQL 16+)

[matthewgreenwaldagility]

Closes crossplane-contrib#359

What this does

Adds a withInherit boolean field to spec.forProvider on the PostgreSQL Grant resource, enabling WITH INHERIT FALSE on role membership grants — a feature introduced in PostgreSQL 16.

apiVersion: postgresql.sql.crossplane.io/v1alpha1
kind: Grant
spec:
  forProvider:
    withInherit: false   # emits: GRANT admin TO master_user WITH INHERIT FALSE
    roleRef:
      name: master-user
    memberOfRef:
      name: admin-role

When withInherit is omitted, behaviour is unchanged. When combined with withOption: ADMIN, the emitted SQL is WITH ADMIN OPTION, INHERIT FALSE.

The field is only valid on memberOf grants — setting it on a privilege grant (privileges field) returns a validation error.

Motivation

The primary use case is RDS PostgreSQL with IAM database authentication. Without this field, granting a master user membership in an admin role that holds rds_iam creates a transitive chain (master_user → admin → rds_iam), which causes RDS to route all connections for that user through PAM/IAM token verification, breaking password authentication. WITH INHERIT FALSE grants membership (satisfying ALTER DEFAULT PRIVILEGES FOR ROLE admin) without inheriting rds_iam.

Changes

File	Change
apis/cluster/postgresql/v1alpha1/grant_types.go	Add WithInherit *bool field to GrantParameters
apis/cluster/postgresql/v1alpha1/zz_generated.deepcopy.go	Regenerated
package/crds/postgresql.sql.crossplane.io_grants.yaml	Regenerated — CRD schema updated
pkg/controller/cluster/postgresql/grant/reconciler.go	New membershipWithClauses helper; selectGrantQuery filters pg_auth_members.inherit_option when set; createGrantQueries uses new helper; validation rejects withInherit on privilege grants
pkg/controller/cluster/postgresql/grant/reconciler_test.go	7 new test cases covering WithInherit nil/true/false for both Observe and Create
examples/cluster/postgresql/grant-with-inherit-false.yaml	New example illustrating the RDS IAM pattern
Makefile	Bump GOLANGCILINT_VERSION from 2.1.2 → 2.10.1 to match CI and support Go 1.26
README.md	Fix stale Go version (1.18→1.26.1), add mise recommendation, fix copy-paste "Developing locally" section (was provider-helm content), add Schema to PostgreSQL resource list, fix example paths

Testing

make reviewable passes (generate + lint + all 26 test packages).

The inherit_option column on pg_auth_members was added in PostgreSQL 16. Setting withInherit on an older cluster will result in a SQL error, which is the expected and documented behaviour.