Fix and improve recursiveCheckDocSchema and first `isSerializable` implementation

[LBRDan]

Hello there! The following PR includes some initial implementations in order to build some momentum for #175 It also implements a fix for the bug about the recursiveCheckDocSchema failing on reporting wrong nested object schema unmatch, found during the development of the schemaless feature for Lyra (here)

The serializability detection has been exposed by @stearm here and freely adapted here as a first implementation. The same detection is extended even on the nested schema object that could trick the current implementation of recursiveCheckDocSchema, apart from the other non matching schema field for schemaless doc fields.

[LBRDan]

Hey @stearm Sounds good to me to implement a new type of error there I was wondering what @micheleriva thinks about it in the linked issue before implementing it

I did an initial implementation very similar to yours but mine lacks of schema level awareness when emitting the error (eg. unserializable property inside a nested object)

[LBRDan]

Superseded by #300 Closing this