Added GoogleApiClient and GoogleApiYoutubeLoader

[Julianwustl]

The current youtube loader is not suitable for use in a production environment because it relies on an uncertified library to interact with the YouTube API. Additionally, it can only handle parsing YouTube links and not channels.

To address these issues, I created a new GoogleApiYoutubeLoader that is capable of building documents based on either a list of video IDs or all videos within a channel. Furthermore, I developed a GoogleApiClient that can be reused for other purposes and offers the necessary features required to run in a production environment.

One note is that I was unable to locate the directory where the tests for other dataloaders are located. If these tests do not exist, I am open to adding tests for my service to ensure its quality and reliability.

Thank you for considering my contributions, and please let me know if there are any further adjustments or concerns that need to be addressed before merging.