Allow algorandAlgodToken to be optional in guardiand for Algorand node integration

[qedgardo]

Description and context

By default, Algorand public APIs require an algod_token to be consumed. However, it also allows the option to disable API authentication. When API auth is disabled, the guardiand service cannot check the Algorand node's block. Currently, if the --algorandAlgodToken argument is removed from the guardiand service configuration, the service fails to start.

Steps to reproduce:

• Disable API authentication on the Algorand node.
• Remove the --algorandAlgodToken argument from the guardiand service configuration.
• Attempt to start the guardiand service.

Expected Behavior:

The guardiand service should start and function correctly, regardless of whether the --algorandAlgodToken is provided, when API authentication is disabled on Algorand node.

Actual Behavior:

The guardiand service fails to start if the --algorandAlgodToken argument is removed from the configuration or set to "".

Definition of done

Update the service configuration to allow --algorandAlgodToken to be optional.

[andreclaro]

@qedgardo api token is required by the Client in go-algorand-sdk: https://github.com/algorand/go-algorand-sdk/blob/a55d63f27569304696d4e49971e3342e0b6bed21/client/v2/common/common.go#L157

The guardiand uses go-algorand-sdk, consequently, if you are getting HTTP 401: {"message":"Invalid API Token"} when passing empty string ("") for algorandAlgodToken, we will need to update go-algorand-sdk to only set the authentication header when api token is not empty.