[lib][keyserver] Use blobURI based on client version

Summary:
The last part of ENG-3966. Details are described in the comments (regarding pt. 4)

This diff introduces a utility function, that constructs a multimedia message based on client version.

Depends on D8373

Test Plan:
CI should finally pass here.

Tested as follows:

• Enabled blob service uploads on both web and native
• Added some console logs to encryptedMediaBlobURI() to display if there's a holder or blobURI.
• On keyserver side, there should always be blobURI.
• The same on web (dev console)
• On native, there should be old format (holder) when minCodeVersion is set to something not yet released (FUTURE_CODE_VERSION) and use blobURI otherwise.

Also tested the following:

• Uploading and displaying encrypted media on Web (both video and images)
• Uploading and displaying encrypted media on Native (both video and images)
• Displaying thread media gallery media on both web and native

Reviewers: ashoat, atul

Reviewed By: ashoat

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D8374