Optional strict handling of BeanMapper mappings

[robert-bor]

Currently, the following convention applies within 42:

• all fields in a Form method must be writable to an Entity
• all fields in a Result method must be readable from an Entity

At the moment this is not enforced. The consequence of this lenient approach is that mappings may fail silently.

It would be beneficial if BeanMapper enforces that all Form/Result properties are mappable to/from an Entity. If this happens at mapping time, a proper error is generated, instead of failing silently.

[robert-bor]

The approach will be the following:

• introduce a property for activating strict mappings for Form and Result classes, default: true
• introduce a property for the suffix of a Form class, default: Form
• introduce a property for the suffix of a Result class, default: Result

When the mapping is made for the first time (this can be checked against the cache), the strict rules must be checked:

• if a getter or public field in a Form class cannot be mapped to the target, throw an exception
• if a setter or public field in a Result class cannot be mapped from the source, throw an exception

On top of these settings, it must be possible to preregister source/target pairs and check these when the BeanMapper bean is created. This is functionality which is similar to Hibernate's ddl-auto=validate.

BeanMapper starter can make use of the preregistrations to component scan annotations which it will supply (BeanMapsTo for Form and BeanMapsFrom for Result). Classes with these annotations and their counterparts will be registered as pairs. As soon as the bean is created, the checks on these pairs will be performed, any failure of which results in an exception.