compose: Remove keyboard focus from stream color block.
compose: Remove keyboard focus from stream color block.

This make `shift-tab` from stream input to `compose_top_right`
buttons directly possible.

rht/zulip,kou/zulip,rht/zulip,zulip/zulip,kou/zulip,andersk/zulip,rht/zulip,zulip/zulip,kou/zulip,rht/zulip,kou/zulip,zulip/zulip,kou/zulip,andersk/zulip,rht/zulip,rht/zulip,andersk/zulip,andersk/zulip,kou/zulip,rht/zulip,zulip/zulip,zulip/zulip,andersk/zulip,zulip/zulip,andersk/zulip,zulip/zulip,andersk/zulip,kou/zulip