Refactor Spring Data R2DBC on top of Spring R2DBC

[mp911de]

Spring Framework aims to include foundational R2DBC support in a similar way to Spring JDBC. We should adopt to these changes by deprecating org.springframework.data.r2dbc.core.DatabaseClient in favor of org.springframework.r2dbc.core.DatabaseClient.

Components on top of DatabaseClient should be rewritten to use Spring Framework's R2DBC variants. In particular:

• Deprecate our DatabaseClient and all necessary infrastructure classes/interfaces
• Deprecate ColumnMapRowMapper and SettableValue
• Adapt AbstractR2dbcConfiguration
• Deprecate connectionfactory package in favor of org.springframework.r2dbc.connectionfactory
• Deprecate support package in favor of org.springframework.r2dbc.connectionfactory
• Use Framework's DatabaseClient in R2dbcEntityTemplate and the repository support classes