chore: More complete tracing for RBAC functions (#5690)

* chore: More complete tracing for RBAC functions
* Add input.json as example rbac input for rego cli

The input.json is required to play with the rego cli and debug
the policy without golang. It is good to have an example to run
the commands in the readme.md

* Add span events to capture authorize and prepared results
* chore: Add prometheus metrics to rbac authorizer

coderd/rbac/authz_internal_test.go

@@ -7,6 +7,7 @@ import (
 	"testing"
 
 	"github.com/google/uuid"
+	"github.com/prometheus/client_golang/prometheus"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"golang.org/x/xerrors"
@@ -41,7 +42,7 @@ func (w fakeObject) RBACObject() Object {
 
 func TestFilterError(t *testing.T) {
 	t.Parallel()
-	auth := NewAuthorizer()
+	auth := NewAuthorizer(prometheus.NewRegistry())
 
 	_, err := Filter(context.Background(), auth, uuid.NewString(), []string{}, ScopeAll, []string{}, ActionRead, []Object{ResourceUser, ResourceWorkspace})
 	require.ErrorContains(t, err, "object types must be uniform")
@@ -160,7 +161,7 @@ func TestFilter(t *testing.T) {
 
 			ctx, cancel := context.WithTimeout(context.Background(), testutil.WaitShort)
 			defer cancel()
-			auth := NewAuthorizer()
+			auth := NewAuthorizer(prometheus.NewRegistry())
 
 			scope := ScopeAll
 			if tc.Scope != "" {
@@ -808,7 +809,7 @@ type authTestCase struct {
 
 func testAuthorize(t *testing.T, name string, subject subject, sets ...[]authTestCase) {
 	t.Helper()
-	authorizer := NewAuthorizer()
+	authorizer := NewAuthorizer(prometheus.NewRegistry())
 	for _, cases := range sets {
 		for i, c := range cases {
 			c := c