feat: support storage accounts without shared key in the table connector and function_app_linux AB#6472

[kfaessen]

Two small additions so storage accounts can run with shared key access turned off.

azure/api_connectors/storage_table_managed_identity (new). The table counterpart of storage_blob_managed_identity. It creates an azuretables connection with the managedIdentityAuth parameter value set, so Logic Apps can read and write tables without the account key. The existing storage_table connector passes the account key, which stops working once shared key is disabled. Tested by deploying the template to a dev resource group: the connection came up as Ready and was removed afterwards. Note for users: a managed identity table connection does not carry the account name, so workflow actions have to use the v2 paths that include the storage account.

azure/function_app_linux: optional use_managed_identity. Same switch as in function_app_linux_managed_identity, but without the app registration and auth settings that module adds. When true the app connects to its backend storage with its system assigned identity and storage_account_access_key can be left out. The default is false, so existing users see no change.

terraform fmt and terraform validate pass for both modules.