In scylladb/scylla#7781 we added possibility to add timeout as part of USING spec.
This patch adds support for it by adding `Timeout` and `TimeoutNamed` functions to builders.
Fixes#194
It allows to write shorter and more straightforward code.
Instead writing:
```
session.Query(qb.Select("cluster").Columns("id").ToCql())
```
you can write:
```
qb.Select("cluster").Columns("id").Query(session)
```
Builder is not in a position to validate the statement and the effort is
duplicated when the query is build. The checked errors are simple and
do not occur most of the time.
