[tx] `transact_builder` is not type-checking input values

[ncalexan]

It appears that transact_builder is not type-checking the provided values, so that, say:

builder.add(sl.clone(), in_progress.get_entid(&ATTR).expect("attr"), TypedValue::typed_string("test")).expect("to add");

and

builder.add(sl.clone(), in_progress.get_entid(&ATTR).expect("attr"), TypedValue::Keyword(kw!(:some/value).into())).expect("to add");

successfully transact. It's not clear to me where in the stack the error is:

• is it that transact in general is not type checking correctly?
• is it that transact_builder, which was added long after the initial transact implementation, is inserting itself into the stack after the type checking is expected to have been done?

In either case this is critical!

[ncalexan]

Oh dear. transact_builder invokes transact_terms

https://github.com/mozilla/mentat/blob/ab957948b4f642e9d4e5e6ac8169c8b382295573/db/src/tx.rs#L785

which invokes transact_simple_terms

https://github.com/mozilla/mentat/blob/ab957948b4f642e9d4e5e6ac8169c8b382295573/db/src/tx.rs#L544

which skips the first stage of the transact pipeline that turns entities into terms... and along the way does all of the schema-aware typechecking

https://github.com/mozilla/mentat/blob/ab957948b4f642e9d4e5e6ac8169c8b382295573/db/src/tx.rs#L532

It's probably not hard to address this, with some slight duplication of work, by growing typechecking assertions in the SchemaTypeChecking trait and invoking them as part of the term processing loop. It will be a little awkward that passing an EDN :keyword/value ident as the value to an attribute of type :db.type/ref will look up the entid for you, but (as written) passing a term TypedValue::Keyword(...) as the value to an attribute of type :db.type/ref won't look up the entid for you... but that's the advantage and disadvantage of using a lower level interface.

[ncalexan]

Addressed by https://github.com/mozilla/mentat/commit/46c2a0801f450f4f62482ee067ed272e1057a747.