Supporting a new type in SeaQuery

[tyt2y3]

Not exactly an issue, but a guide on how to support a new type in SeaQuery.

1. It usually starts from ColumnType where we'd add the type, so that it can be used in schema statements
2. If the type has a native representation (like UUID), we can add a variant to the enum Value (and ArrayType) and implement all necessary traits (ValueType)
3. we should also determine the JSON serialisation (most likely string) which is implemented in sea_value_to_json_value
4. Feature guards i.e. #[cfg(feature = "with-uuid")] are needed
5. We shouldn't depend on sqlx directly in the sea-query crate, so if a type is only defined in sqlx, we have to copy the struct and put it inside sea-query
6. In sea-query-binder & sea-query-postgres, we then perform the type conversion and binding
7. Finally, in sea-orm, we should implement TryGetable for the right backend

Reference:

(ipnetwork)
#309
#364
#503

(time)
#267
SeaQL/sea-orm#602