Parsing support

`sjs` could be able to support parsing functionality aswell. During the `schema-creation` phase, a template is created in memory. Providing a handful way of inserting values inside it during `serialization`.

It would be possible to leverage that same information in order to retrieve (parse) information faster as the template knows exactly where they were inserted in the first place.

Ofc, this would be guaranteed to work only when the parser and the serializer are sharing the same schema

Start by reading the schema-creation and serialization flow to understand how the in-memory template records inserted values. Then determine how a parser could reuse that schema when paired with the serializer, and define the supported behavior and tests for schemas shared by both. The issue does not name specific files or existing tests.

Written by the indexing model from the issue text.