New implementation of network service

src/sakia/core/community.py

src/sakia/core/net/__init__.py

src/sakia/core/net/api/bma/__init__.py

src/sakia/core/net/node.py

src/sakia/data/connectors/__init__.py

src/sakia/data/connectors/bma.py

src/sakia/data/connectors/node.py

src/sakia/data/entities/node.py

src/sakia/data/processors/__init__.py

src/sakia/data/processors/nodes.py

src/sakia/data/repositories/meta.sql

src/sakia/data/repositories/nodes.py

src/sakia/errors.py

src/sakia/services/__init__.py

src/sakia/services/network.py

src/sakia/tests/technical/__init__.py

src/sakia/tests/technical/test_network_service.py

src/sakia/tests/unit/core/test_network.py

src/sakia/tests/unit/core/test_node.py

src/sakia/tests/unit/data/test_node_connector.py