Updated the direct file upload/download to use the non-base64 approaches as well
Updated the attachment 'serverId' value to be a string instead of a UInt64 (future-proofing)
Updated the OnionRequest V4 response handling to avoid converting the "response body" part to a string and processing that, instead just slice the byte array (ie. stopped it from being broken from multiple conversions)
Removed the base64-based file upload/download endpoints (no use including them when they are inefficient and we don't want to use them)
Fixed a bug where sharing a text file was resulting in the entire contents being put into the message input field
Fixed a bug where sharing from within the app where the app was in dark mode but the device was in light mode would result in buggy UI
Updated the share extension to load URL previews.
Updated the ThreadPickerVC to send plain text & URLs in the same way they are sent for normal messages.