Switch wording for Witness Schedule & Last Updated to font awesome icons

Let us switch from using the wording "Check Witness Schedule" in the witnesses page to use a font awesome icon representing schedule with a tooltip text saying "Witness Schedule". On click this will open the schedule page as is the current behaviour.

A good icon to use is https://fontawesome.com/icons/calendar-days?f=classic&s=solid

Similarly, instead of the wording "Last updated: 10 mins ago" let us use also a font awesome icon with a tooltip that says "Last Updated - MINS ago" ( with the wording MINS being updated dynamically). The icon color would be green if the last update is within 10 mins, it would be orange if within 1 hour, it would be light red if more than 1 hour.

A good icon to use is https://fontawesome.com/icons/clock?f=classic&s=regular