Create `TestBlobStorageConfig` test configuration instance for test-friendly Azure Blob storage authentication

[stijnmoreels]

Is your feature request related to a problem? Please describe.
When interacting with Azure Blob storage, we need some information to make the interaction/authentication successful. Instead of burdening the tester with each piece of this information separately, we need a more streamlined and scalable approach on loading the required information in a 'test config' model and use it in any following Azure Blob storage-related test functionality.

Describe the solution you'd like
Create a dedicated TestBlobStorageConfig model that loads configuration keys from the TestConfig (#92). The required information is:

• The Azure Storage Account name
• The (optional) connection string (default: DefaultTokenCredential)

The configurtion has all the necessary information to create a BlobServiceClient.

Additional context
#92 #93

[stijnmoreels]

Will not be needed due to the way we will support all authentication mechanisms and leave the flexibility of loading test confirmation values.