Updates frontend user-facing strings with "private message" or "PM" to
use "direct message" or "DM" respectively instead.
Note that this updates translated strings as well as a few that
are not translated like search suggestions.
Updates `tools/lib/capitalization.py` for some specific strings
that are impacted by these changes, and removes "PM" and "PMs"
from checked strings.
This lets us simplify the long-ish ‘../../static/js’ paths, and will
remove the need for the ‘zrequire’ wrapper.
Signed-off-by: Anders Kaseorg <anders@zulip.com>
Anders Kaseorg
Lauryn Menard