Add a limit on files upload

[misstick]

• [x] add a message about files limitation number (into view and console),
• [x] add files limitation on upload,
• [x] define a limit of files size to be uploaded -> 1000,

see https://github.com/cozy/cozy-files/issues/365

[misstick]

@CPatchane, @m4dz : I'm not sure about the value to choose about max files limitation for upload; would you have any idea about this?

[CPatchane]

@misstick If that works with 1000 items, that could be a correct number to my mind.

[m4dz]

Agree w/ @CPatchane: I've never encoutered this one and I can upload sometimes something like ~500 files at a time. So a high value like 1000 seems to be reasonnable to me.