Adds supports for most of the features from the wonderful typed_ecto_schema library.

Rather than using the typed_embedded_schema macro from that library, however, thr Typed extension incorporates the features into the standard embedded_schema macro from Flint.Schema, meaning even fewer lines of code changed to use typed embedded schemas!

Included with that are the addtional Schema-Level options you can pass to the embedded_schema macro.

You also have the ability to override field typespecs as well as providing extra field-level options from typed_ecto_schema.

Required vs Enforced vs Null

Note that the typespecs allow you to specify :enforce and :null options, which are different from the requirement imposed by field!.

---

field! marks the field as being required during the changeset validation, which is equal to passing the field name to the Eco.Changeset.validate_required/3. An instance of the schema's struct CAN still be created if a field marked with field! is not present.

---

enforce: true is equal to including that field in the @enforce_keys module attribute for the corresponding schema struct.

An instance of the schema's struct CANNOT be created if a field marked with enforce: true is not present, as it will raise an ArgumentError.

---

:null indicates whether nil is a valid value for the field. This only impacts the generated typespecs.