get_interchain: per_chain + chains options (default first anchor per chain); bump 0.5.0

transaction.get_interchain / block.get_interchain take per_chain= and chains=
kwargs mapping to prime-node's ?perChain=&chains= params. Default (no kwargs)
returns one anchor per chain. Shared interchain_query() helper, exported; pytest.

prime_sdk/__init__.py

@@ -81,6 +81,7 @@ from .models import (
     SecurityResult,
     TransactionReport,
 )
+from .interchain import interchain_query
 from .proof_measure import DEFAULT_BASE_URL as PROOF_MEASURE_DEFAULT_BASE_URL
 from .proof_measure import ProofMeasureClient
 from .system import SystemClient
@@ -88,7 +89,7 @@ from .transaction import TransactionClient
 from .transaction_type import TransactionTypeClient
 from .unauthenticated_client import UnauthenticatedClient
 
-__version__ = "0.4.0"
+__version__ = "0.5.0"
 
 
 class DragonchainSDK:
@@ -148,6 +149,7 @@ __all__ = [
     "ProofMeasureClient",
     "UnauthenticatedClient",
     "PROOF_MEASURE_DEFAULT_BASE_URL",
+    "interchain_query",
     # models
     "Block",
     "BlockHeader",