OGM-454 Moving internal types to "impl" packages
OGM-454 Moving SPI types to "spi" packages
OGM-454 Moving OptionConfigurator to API package
OGM-454 Avoiding FQNs in JavaDocs of public types
OGM-454 Marking GridType and GridDialect#overrideType() with @Experimental
OGM-454 Extracting interface from class ConfigurationContext to avoid leaking impl types on SPI contracts
OGM-454 Splitting up ConfigurationPropertyReader into SPI and implementation part to avoid leakage of impl type on SPI contract
OGM-454 Moving some types intended for usage in dialects from "impl" to "spi"

* configuration context base classes
* option types
* id generators
* generic option model for dialects without options
OGM-454 Moving AssociatedEntityKeyMetadata next to other metadata objects into "grid" package