Optimize SQLite writes with manual commits

src/sakia/app.py

src/sakia/data/connectors/node.py

src/sakia/data/processors/blockchain.py

src/sakia/data/processors/certifications.py

src/sakia/data/processors/identities.py

src/sakia/data/processors/sources.py

src/sakia/data/processors/transactions.py

src/sakia/data/processors/tx_lifecycle.py

src/sakia/data/repositories/blockchains.py

src/sakia/data/repositories/certifications.py

src/sakia/data/repositories/connections.py

src/sakia/data/repositories/identities.py

src/sakia/data/repositories/meta.py

src/sakia/data/repositories/nodes.py

src/sakia/data/repositories/sources.py

src/sakia/data/repositories/transactions.py

src/sakia/gui/dialogs/connection_cfg/controller.py

src/sakia/gui/dialogs/connection_cfg/model.py

src/sakia/services/blockchain.py

src/sakia/services/identities.py