Add storage attribute fields + remove storageTier field

[hossainemruz]

Ticket: CRC-1366

This PR adds following fields.

// Storage specifies the storage specification for the PVCs of the cluster. If the field is not set, no configuration will be applied.
// +optional
Storage *Storage `json:"storage,omitempty"`

type Storage struct {
	// VolumeAttributesClassName specifies VolumeAttributeClass name to use for the storage PVCs
	// +optional
	VolumeAttributesClassName *string `json:"volumeAttributesClassName,omitempty"`
	// IOPS defines the IOPS number to configure for the storage PVCs
	// +optional
	IOPS *int `json:"iops,omitempty"`
	// Throughput defines the throughput number in MB/s for the storage PVCs
	// +optional
	Throughput *int `json:"throughput,omitempty"`
}

It also removes following unused field.

// StorageTier specifies the performance tier to use for the disk
// +kubebuilder:validation:Enum=budget;balanced;performance
// +optional
StorageTier *StorageTier `json:"storageTier,omitempty"`