Add bulk query operations

[stevebauman]

This PR adds the ability to perform bulk message operations on a folder. For example:

// Single message operations
$message->markRead();
$message->move('Archive');
$message->delete();

// Batch message operations
$folder->messages()->unseen()->markRead();
$folder->messages()->before('2023-01-01')->move('Archive');
$folder->messages()->from('spam@example.com')->delete();