Merge all the work done so far for the 3.0.0 release into master

Drop db support for PostgreSQL 9.3 and MariaDB 10.0

Removed Driver::getDatabase() in favor of Connection::getDatabase()

Remove support for sharding and the Azure platform

Make sure that (VAR)CHAR column length is specified in characters, not bytes

Removed some unused code bits

Enable phpstan in DBAL tests

Get rid of hard-coded default values of maximum field lengths

Getting rid of the column name index

Remove LoggerChain::addLogger

Enforce parameter and return value types in the codebase

Enforced parameter and return value types in event-related classes

Add proper types to Doctrine\DBAL\Query namespace.

Add proper types to root Doctrine\DBAL namespace.

Add proper types to Doctrine\DBAL\Id namespace.

Add proper types to the Doctrine\DBAL\Sharding namespace.

Add proper types to Doctrine\DBAL\Tools namespace.

Enforced parameter and return value types in Connection classes

Add proper types to Doctrine\DBAL\Types namespace.

Add types to Schema namespace