Define a contract for `spec-tools/spec` and `schema-tools/schema`

Same contract for both for easy travel in between:

```clj
(schema-tools.core/spec
integer?
{:description "kikka"
:type-hint :long
:default 1})

(schema-tools.core/schema
Long
{:description "kikka"
:default 1})
```

Relates https://github.com/metosin/spec-tools/issues/23

Start by reading the schema-tools.core/spec and schema entry points and the related spec-tools issue 23. Compare the two example calls and determine the shared contract and option behavior; done means both entry points follow the agreed contract for equivalent inputs.

Written by the indexing model from the issue text.