PresenceStatusIndicator: Rework to match web visuals
PresenceStatusIndicator: Rework to match web visuals

An important and needed refactor is splitting each type of indicator
in a spearate component as we could not achieve this with only a
style change (we can do that on the web with the richer CSS supported).

Changes are as follows:
 * active - no white border, orange is the same color but used the
   same `hsl` way of specifying the color as on the web
 * idle - now sports the same semi-circle we have on the web
 * offline - color changed to 'gray' to match web
 * unavailable - same color and line as we already have on the web

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