Remove exif info from image uploads

[zeerooth]

Resolves #263

Supports jpeg, png and webp (just like img-parts)

Some things to still consider:

• Unfortunately, to parse the image and manipulate it we have to load it whole into the memory, but I don't think there's any way around that, especially when looking at currently available libraries.
• Should we lock this behaviour behind a feature/config option? I personally think it's best not to make it opt-out.
• We don't know what the file size is going to be in the multipart upload, so I use BytesMut without any capacity, which means it has to reallocate when receiving new stream chunks. This is unfortunate but again, I don't think there's a way around that aspect too.

[aumetra]

just some small nits

[aumetra]

this looks fine, I would keep it as something that is just forced on the users. I don't like the idea that an instance could accidentally let users post their geolocation.

And yeah, it's not possible to do without buffering with current crates unfortunately. I wanna check for better alternatives but until then I would just add this

[aumetra]

Looks good now, thanks!