Add support for DefaultAzureCredentials instead of connection string

[bkotar1]

Its better to add the support for defaultazurecredentials for this sink as storing the connection string is not needed.

[pwelter34]

You can do that already by creating a TableServiceClient.

 // Replace with your actual Azure Table Storage endpoint
string tableEndpoint = "https://yourstorageaccountname.table.core.windows.net/"; 

// Create DefaultAzureCredential
var credential = new DefaultAzureCredential();

// Create TableServiceClient with the endpoint and credential
var tableServiceClient = new TableServiceClient(new Uri(tableEndpoint), credential);

https://github.com/serilog-contrib/serilog-sinks-azuretablestorage?tab=readme-ov-file#example-using-defaultazurecredential