InfoItem: Fix an `any` to the much more specific `mixed`.
InfoItem: Fix an `any` to the much more specific `mixed`.

This value could be anything... and seriously it could be anything
and the code would be fine.  (Because the one thing it does with it
is pass it to JSON.stringify.)  That is a pretty strong constraint on
this code -- great!  The way to say that is `mixed`.

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