feat: adds aws ebs config (#192)

Implements the CSI driver for AWS EBS as well as a "defaultStorageClass"
option.

A user can test this functionality with CAPA clusters with the following
under the main cluster config variable

```
   addons: 
            csi:
              providers:
                - name: aws-ebs
              defaultClassName: aws-ebs
```

---------

Co-authored-by: Dimitri Koshkin <dimitri.koshkin@gmail.com>

Author: faiq

api/v1alpha1/clusterconfig_types.go

@@ -16,6 +16,7 @@ import (
 
 const (
 	CNIProviderCalico = "calico"
+	CSIProviderAWSEBS = "aws-ebs"
 )
 
 //+kubebuilder:object:root=true
@@ -320,6 +321,9 @@ type Addons struct {
 
 	// +optional
 	NFD *NFD `json:"nfd,omitempty"`
+
+	// +optional
+	CSIProviders *CSIProviders `json:"csi,omitempty"`
 }
 
 func (Addons) VariableSchema() clusterv1.VariableSchema {
@@ -330,6 +334,7 @@ func (Addons) VariableSchema() clusterv1.VariableSchema {
 			Properties: map[string]clusterv1.JSONSchemaProps{
 				"cni": CNI{}.VariableSchema().OpenAPIV3Schema,
 				"nfd": NFD{}.VariableSchema().OpenAPIV3Schema,
+				"csi": CSIProviders{}.VariableSchema().OpenAPIV3Schema,
 			},
 		},
 	}
@@ -369,6 +374,45 @@ func (NFD) VariableSchema() clusterv1.VariableSchema {
 	}
 }
 
+type CSIProviders struct {
+	// +optional
+	Providers []CSIProvider `json:"providers,omitempty"`
+	// +optional
+	DefaultClassName string `json:"defaultClassName,omitempty"`
+}
+
+type CSIProvider struct {
+	Name string `json:"name,omitempty"`
+}
+
+func (CSIProviders) VariableSchema() clusterv1.VariableSchema {
+	supportedCSIProviders := []string{CSIProviderAWSEBS}
+	return clusterv1.VariableSchema{
+		OpenAPIV3Schema: clusterv1.JSONSchemaProps{
+			Type: "object",
+			Properties: map[string]clusterv1.JSONSchemaProps{
+				"providers": {
+					Type: "array",
+					Items: &clusterv1.JSONSchemaProps{
+						Type: "object",
+						Properties: map[string]clusterv1.JSONSchemaProps{
+							"name": {
+								Type: "string",
+								Enum: variables.MustMarshalValuesToEnumJSON(
+									supportedCSIProviders...),
+							},
+						},
+					},
+				},
+				"defaultClassName": {
+					Type: "string",
+					Enum: variables.MustMarshalValuesToEnumJSON(supportedCSIProviders...),
+				},
+			},
+		},
+	}
+}
+
 func init() {
 	SchemeBuilder.Register(&ClusterConfig{})
 }