Changes Dbal\DatabaseName, Dbal\TableName and Triggers\TriggerName to
implements the new Identifier\Identifier interface.
Moves Dbal\DatabaseName, Dbal\TableName and Triggers\TriggerName to the
Identifiers namespace.
Renames the tryFromValue() and fromValue() methods to just tryFrom() and
from() respectively.
Signed-off-by: Maurício Meneghini Fauth <mauricio@fauth.dev>
