[FEATURE]: Simplify process of creating secrets for GrantBucketAccess

[shanduur]

Are you interested in contributing to the development of this feature?

Yes

Is your feature request related to a problem? Please describe.

The credentials returned in the Driver is of type map[string]string. It is sometimes confusing to new developers how to structure this value for available protocols.

Describe the solution you'd like.

I would like to have functions that simplify the creation of the credentials, e.g.:

func S3Credential(secretKeyID, secretKey, bucketName string, endpoint *url.URL) (map[string]string, error)

Additionally, for the purpose of custom functions that can be written in the future, provide each map key in form of constant, e.g.:

import "sigs.k8s.io/container-object-storage-interface-provisioner-sidecar/pkg/consts"

const (
	S3SecretAccessKeyID string = consts.SecretAccessKeyID
	// ...
)

Describe alternatives you've considered.

Importing the sigs.k8s.io/container-object-storage-interface-provisioner-sidecar/pkg/consts and creating the credentials by hand.

Additional Information

N/A