support set MaxIdleConns MaxOpenConns ConnMaxLifetime from dsn

[hanjm]

Is your feature request related to a problem? Please describe.
Currently, we can set most option from dsn, but can not set MaxIdleConns MaxOpenConns ConnMaxLifetime

clickhouse-go/clickhouse_options.go

Lines 260 to 265 in b0a69d7

	}
	case "connection_open_strategy":
	switch params.Get(v) {
	case "in_order":
	o.ConnOpenStrategy = ConnOpenInOrder
	case "round_robin":

Describe the solution you'd like
Support set from dsn.

[jkaflik]

@hanjm
In case you use database/sql, setting those options have no effect, since connection pool is managed by database/sql - please see: https://github.com/ClickHouse/clickhouse-go#opendb

I think it was omitted mostly because of it, but since we expose clickhouse.ParseDSN to be used with our API, it makes sense to support connection pool options in DSN parser as well.

Would you like to submit a PR for it?