[native] Update thumbnailID upon successful thumbnail upload

Summary:
Need to include the thumbnailID in addition to the thumbnailURL in the updateMediaPayload.

Depends on D5059

Test Plan:
sendMultimediaMessage in subsequent diff gets correctly constructed mediaMessageContents with expected values.

Reviewers: abosh, tomek, marcin

Reviewed By: tomek

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D5060