Rename common abstract class for profilePhoto and chatPhoto to QTdBasePhoto

This avoids collisions with tdlib docs, as photo is another class there, currently implemented as QTdPhotos, which is renamed to QTdPhoto

For reference: https://core.telegram.org/tdlib/docs/classtd_1_1td__api_1_1photo.html https://core.telegram.org/tdlib/docs/classtd_1_1td__api_1_1chat_photo.html https://core.telegram.org/tdlib/docs/classtd_1_1td__api_1_1profile_photo.html