Add a new AERONET stream - lunar measurements

Hello @dbowdalo

Just I've opened this issue to start planning to add a new AERONET stream in the GHOST dataset. It's the "Version 3 Provisional Direct Moon Algorithm".

We will need to revise the information about the instrument and the retrieval, but it's quite straightforward because the variables are the same as in the case of directsun formatting. The technical report can be found here: doc1 and doc2

Cheers

Sara