Edit CLI Short of Creation of Type aws-sts-s3 in BS and NS

[shirady]

Explain the changes

1. Edit noobaa CLI short of creation of noobaa backingstore create aws-sts.
2. Add validation to aws-sts-arn that the user enters.
3. Add the above changes to noobaa namespacestore create aws-sts.

Issues: Fixed #xxx / Gap #xxx

1. none, I thought that the description creates an expectation to see a new type of aws-sts-s3 which is not true (it is aws-s3), hence suggesting to change it.

Testing Instructions:

To see the new changes in the noobaa CLI build the image using make cli.

1. noobaa backingstore create --help attached partial output:

Available Commands:
aws-s3 Create aws-s3 backing store (using long-lived credentials)
aws-sts-s3 Create aws-s3 backing store (using STS, short-lived credentials)

2. noobaa namespacestore create --help attached partial output:

Available Commands:
aws-s3 Create aws-s3 namespace store (using long-lived credentials)
aws-sts-s3 Create aws-s3 namespace store (using STS, short-lived credentials)

To see the changes related to the aws-sts-arn validation

1. Create AWS STS Setup on Minikube (the guide will be in the operator repo, meanwhile this is the PR #Doc | Create AWS STS Setup on Minikube Dev Guide #1244.
2. Build the image and deploy noobaa on MInikube (see guide).
   Note: nb is an alias that runs the local operator from build/_output/bin (alias created by devenv).
3. Create backingstore:
   nooba backingstore create aws-sts-s3 <backingstore-name> -n <your-namespace>
   Then in the prompted Enter aws-sts-arn: type a short string, for example: 'dd'
   You'll see a message:

FATA[0001] ❌ aws-sts-arn "dd" is invalid

4. 3. Create namespacestore:
      nooba namespacestore create aws-sts-s3 <namespacestore-name> -n <your-namespace>
      Then in the prompted Enter aws-sts-arn: type a short string, for example: 'dd'
      You'll see a message:

FATA[0001] ❌ aws-sts-arn "dd" is invalid

• Doc added/updated
• Tests added