Client-side validation of file size

[ARMmaster17]

Summary

As of right now, as part of the OWASP recommendations for websites, we do not allow uploads of files of arbitrary sizes. Instead the underlying Tomcat server caps the size of all incoming multipart file uploads to 4 MB. The front-end currently has no knowledge of this, and uploading of a file bigger than 4 MB will lead to a strange error.

Blocked by #26 and #57

Implementation

• Add client-side validation on file upload fields that blocks uploads larger than 4 MB.
• Add a helpful error message when the file is too large.
• Write E2E test that creates a randomly generated file larger than 4 MB and attempts to upload it.
• (OPTIONAL) Modify the upload size limit in src/main/resources/application.yml (see comments).

Comments

• The 4 MB size limit is defined by us, and we can change it if needed. It might be a good idea to look at the rough size of a ~5 page PDF documents with words and images and adjust this limit accordingly.

[ARMmaster17]

Moving this to sprint three, as since we're probably going to do a controlled demo, we don't need this until the final presentation.