Get context menu item from the ArrayAdapter instead of message index.
Get context menu item from the ArrayAdapter instead of message index.

Message index is not populated in narrowed views.

prati0100/zulip-android,zulip/zulip-android,saketkumar95/zulip-android,Sam1301/zulip-android,prati0100/zulip-android,saketkumar95/zulip-android,abhaymaniyar/zulip-android,vishwesh3/zulip-android,Sam1301/zulip-android,abhaymaniyar/zulip-android