Limit the avatar file size

[satazor]

Description

We should limit the avatar file size to avoid having large image files. Something like 2MB. Also, we should apply this limit when fetching the image itself. This protects against people fetching a profile of someone that bypassed this limit. To do this, we may use the getPullStream and read up to that limit in bytes.

Acceptance Criteria

• [ ] Apply the limit when choosing an avatar; we need to decide where to present the error message
• [ ] Apply the limit when reading the image from IPFS