refactor(coderd/database): split Time and Now into dbtime package (#9482)

Ref: #9380

coderd/database/dbtime/dbtime.go

@@ -0,0 +1,14 @@
+package dbtime
+
+import "time"
+
+// Now returns a standardized timezone used for database resources.
+func Now() time.Time {
+	return Time(time.Now().UTC())
+}
+
+// Time returns a time compatible with Postgres. Postgres only stores dates with
+// microsecond precision.
+func Time(t time.Time) time.Time {
+	return t.Round(time.Microsecond)
+}