MAINT-2787: Expand viewer_manifest.py's "Release" recognition

viewer_manifest.py currently detects specifically the channel name "Second
Life Release" as a release viewer (affecting the icon and other things). The
Amazon viewer uses channel name "Second Life Release - Amazon", which is
currently not recognized at all, therefore uses a developer-build icon with
the caution tape and the word "TEST" stamped onto it. Detect any channel name
*starting* with "Second Life Release" as a release viewer.