Create scheduler to extract data from tenant

The scheduler must be run per tenant and extracts the following information for each tenant:

• the number of uploaded files (documents with a "file:content" not null)
• the size of all the uploaded files
• the total size of files in the tenant (main blob, conversions and thumbnails)
• the total size of conversions

For the number of uploaded files and their size, make a distinction between Background and Asset (subdivised between Video, Audio and Picture)

The scheduler must run one worker per tenant and be scheduled at midnight every day.