i18n types: Add a read-only mark in the argument to withGetText.
i18n types: Add a read-only mark in the argument to withGetText.

This should always be satisfied -- this is a prop of a React
component, after all -- and it's perhaps a bit clearer to make
it explicit.

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