compatibility: Pull logic out of message string.
compatibility: Pull logic out of message string.

This doesn't directly matter here (i.e., this is a pure refactor)
because we don't currently translate these messages, because this
logic lives near the outside of the app with very few dependencies.
But still we might as well use the same pattern that's good practice
almost everywhere else.

vishwesh3/zulip-mobile,vishwesh3/zulip-mobile,vishwesh3/zulip-mobile,vishwesh3/zulip-mobile