This commit introduces a DataSource proxy, that changes the behavior of the getConnection method to use the `createConnectionBuilder()` api to acquire direct shard connections. The shard connection is acquired by specifying a `ShardingKey` that is correspondent to the wanted shard.

The sharding key can be specified either by setting the thread bound sharding key value, which will be used later by the `getConnection()` method, or by defining a `ShardingKeyProvider` which is used in the `getConnection` method to get the ShardingKey.

If both ways are used at the same time, the thread-bound sharding key is the one that will be used.

The goal of binding the sharding key to the current thread, is that we want to specify the sharding key at one level, and want it to be used later in another level, without the need to propagate it, for example set the thread-bound sharding key, and execute a `JdbcTemplate.query(SQL)` method that that will call `DataSource.getConnection()`, and as the sharding key is bound to the thread, it can be acquired to get the shard connection.