The simplebar is the default scrollbar throughout majority of Zulip but
it was missing in "Keyboard shortcuts", "Message formatting" and "Search
operators" modals. Added simplebar in the 3 modals.
Add ability to search entire message history of all public streams at
once. It includes all subscibed, non subscribed public streams messages
and even historical public stream messages sent before user had joined
an organization or stream.
Fixes#8859.
Makes the i18n strings in this file much easier to translate by splitting
them into smaller chunks (which avoids having a lot of code in the tagged
strings), and adds a string that was missing as well.
This should make it easier to find the templates that are actually
part of the core webapp, instead of having them all mixed together
with the portico pages.