Feature Request: Add a file upload size limit

[kszalwinski-rbi]

Is your feature request related to a problem? Please describe.

I am facing the problem of users who upload huge files to our Sanity through the stanity-plugin-media.
When uploading the assets through stanity-plugin-media non of the custom validators is triggered.

Describe the solution you'd like
I would like to configure that MAX_ALLOWED_ASSET_SIZE environment variable that will define the maximum size of the asset being uploaded through stanity-plugin-media.

Describe alternatives you've considered
Alternatively the property could provided as a custom argument when loading stanity-plugin-media in defineConfig function.