Expose the driver from the library

**Is your feature request related to a problem? Please describe.**

Trying to use a variety of methods which wrap an sql `driver.Driver` interface, which is exported in for example the MySQL and Postgres drivers (and many others) but not the clickhouse one. Example would be the use of the `sqlhooks` (see https://github.com/qustavo/sqlhooks) library to debug queries sent to the driver and the responses/parameters passed in

**Describe the solution you'd like**
change `type clickhouse struct` to `type Clickhouse struct` and update the relevant methods on the struct.

**Describe alternatives you've considered**
Alternative would be to write a complete set of wrappers for all methods on the driver.

Start by locating the unexported `type clickhouse struct` and the relevant methods on it. Check how the driver satisfies `database/sql/driver.Driver` and review sqlhooks usage; done means the driver is exposed for wrapping without requiring a separate wrapper for every method.

Written by the indexing model from the issue text.