feat: introduce Data Access Object

[ethicnology]

⚠️ This refactoring should not be included in 6.5.0

This design pattern is used to abstract and encapsulate all access to the database by extracting queries into classes that are available from your main database class.

This will also simplify our life if one day we have to replace drift, since these classes have to be injected.

Currently we have one DAO per table, but we can design more complex DAO accessing multiple tables in the future.

The next step will be to replace 73 direct database accesses across 13 datasources

Datasource	Queries to Replace	DAO to Use
settings_datasource.dart	into().insert, managers.settings.filter().getSingle, 10x managers.settings.update	SettingsDao
wallet_metadata_datasource.dart	into().insertOnConflictUpdate, managers.walletMetadatas.filter().getSingleOrNull, managers.walletMetadatas.get(), managers.walletMetadatas.filter().delete()	WalletMetadatasDao
label_datasource.dart	managers.labels.create, batch(), 2x managers.labels.filter().get(), 3x managers.labels.filter().delete(), managers.labels.get(), selectOnly(), delete().go()	LabelsDao
boltz_storage_datasource.dart	3x into().insertOnConflictUpdate, 2x select().where().getSingle, managers.swaps.filter().getSingleOrNull, managers.swaps.filter().get(), managers.swaps.filter().delete()	SwapsDao, AutoSwapDao
local_payjoin_datasource.dart	2x into().insertOnConflictUpdate, 2x managers.filter().getSingleOrNull, 4x managers.filter().get()	PayjoinSendersDao, PayjoinReceiversDao
electrum_server_storage_datasource.dart	into().insertOnConflictUpdate, batch(), 4x managers.electrumServers.filter().get(), managers.electrumServers.filter().delete()	ElectrumServersDao
electrum_settings_storage_datasource.dart	into().insertOnConflictUpdate, managers.electrumSettings.get(), 2x managers.electrumSettings.filter().get/getSingle()	ElectrumSettingsDao
electrum_remote_datasource.dart	managers.transactions.filter().getSingleOrNull, into().insert	TransactionsDao
mempool_server_storage_datasource.dart	into().insertOnConflictUpdate, managers.mempoolServers.filter().getSingleOrNull, managers.mempoolServers.filter().delete()	MempoolServersDao
mempool_settings_storage_datasource.dart	into().insertOnConflictUpdate, managers.mempoolSettings.filter().getSingleOrNull	MempoolSettingsDao
bip85_datasource.dart	managers.bip85Derivations.create, 3x managers.bip85Derivations.filter().get/getSingleOrNull, 3x managers.bip85Derivations.filter().update	Bip85DerivationsDao
recoverbull_settings_datasource.dart	into().insertOnConflictUpdate, 2x managers.recoverbull.filter().getSingle, managers.recoverbull.update	RecoverbullDao
price_local_datasource.dart	batch(), select().where(), 2x delete().where()	PricesDao

[ethicnology]

DAO are not as useful as expected in the planned Architecture where each feature is encapsuling database calls