Add an icon corresponding to sensor.svg in element-web

[rbondesson]

Context

Add an icon corresponding to sensor.svg in element-web to avoid using svg-files when refactoring components into the shared components library.

https://github.com/element-hq/element-web/blob/develop/res/img/sensor.svg

Screenshot

[americanrefugee]

For the send timestamp use the Send Solid icon. The color should be color/icon/secondary.

[rbondesson]

The element web team went for the option to not move the rendering of sensors.svg to shared components.
Closing this issue as won't fix.