Engine: Disabling Validation result in suboptimal compilation of structural record operations.

Ast expressions EStructProjand EStructUpd are compiled deferentially depending on the variable field var fieldIndex: Optional[Int].

• If fieldIndex is undefined the lookup of the field to update/project is done by name (i.e. linear in number of the structural record fields)
• If fieldIndex is defined to an integer idx, this later is used as the field index to look up, resulting in constant time operation).

This field is undefined by default and is only set by the type checking pass. Therefore when the validation is skipped (by setting the field packageValidation to false in the EngineConfig), the compilation of structural record of projection and update is sub-optimal.

[remyhaemmerle-da]

Another option is to do the slow linear lookup when executing EStructProj for the first time, but then cache the index and reuse it after the first execution. It should always be the same index.

This is also an interesting idea (that can be combine with 1).

[remyhaemmerle-da]

fixed by #12338.