Remove type parameter from QuerySpec

[javier-godoy]

- QuerySpec<K extends Serializable>
+ QuerySpec

This is a breaking change.

[mlopezFC]

Maybe instead of K meaning a key, we could use T meaning an entity, that might be useful to avoid a lot of castings.

[javier-godoy]

Note that no castings are involved because QuerySpec is not typed (fields are referenced as string).

What would be the signature of this method?
https://github.com/AppJars/commons-backend/blob/cc07f0892e0ca613803036fb2d639e47ce522ce9/commons-business-impl/src/main/java/com/appjars/saturn/service/ConversionQueryServiceMixin.java#L61

with

https://github.com/AppJars/commons-backend/blob/cc07f0892e0ca613803036fb2d639e47ce522ce9/commons-business-impl/src/main/java/com/appjars/saturn/service/ConversionQueryServiceMixin.java#L39-L43

The DAO will expect QuerySpec<P> but we cannot have List<B> filter(QuerySpec<P>) in the service layer (because the view cannot* be required to care about the type of persistence layer entity).