DRA CEL: add missing size estimator

Not implementing a size estimator had the effect that strings retrieved from
the attributes were treated as "unknown size", leading to wildly overestimating
the cost and validation errors even for even simple expressions like this:

    device.attributes["qat.intel.com"].services.matches("[^a]?sym")

Maximum number of elements in maps and the maximum length of the driver name
string were also ignored resp. missing. Pre-defined types like
apiservercel.StringType must be avoided because they are defined as having
a zero maximum size.

Kubernetes-commit: f89e4c08cfe37ba0303a3994ce6e78765231b518

Author: pohly

resource/v1alpha3/types.go

@@ -145,6 +145,10 @@ type ResourceSliceSpec struct {
 	Devices []Device `json:"devices" protobuf:"bytes,6,name=devices"`
 }
 
+// DriverNameMaxLength is the maximum valid length of a driver name in the
+// ResourceSliceSpec and other places. It's the same as for CSI driver names.
+const DriverNameMaxLength = 63
+
 // ResourcePool describes the pool that ResourceSlices belong to.
 type ResourcePool struct {
 	// Name is used to identify the pool. For node-local devices, this

resource/v1beta1/types.go

@@ -144,6 +144,10 @@ type ResourceSliceSpec struct {
 	Devices []Device `json:"devices" protobuf:"bytes,6,name=devices"`
 }
 
+// DriverNameMaxLength is the maximum valid length of a driver name in the
+// ResourceSliceSpec and other places. It's the same as for CSI driver names.
+const DriverNameMaxLength = 63
+
 // ResourcePool describes the pool that ResourceSlices belong to.
 type ResourcePool struct {
 	// Name is used to identify the pool. For node-local devices, this