LIMS-1286: Show ERA status on calendar and visits list

[ndg63276]

JIRA ticket: LIMS-1286

Summary:

Users (and staff) often don't realise their ERA has not been validated as the visit approaches, so we should display it more prominently.

Changes:

• Get risk rating for each session from ISPyB (it should be synced to UAS)
• Display a green/yellow/red circle for low/medium/high risk sessions, and a black circle if the ERA has not been approved yet, on both the calendar page and also the visits list page
• Display a tooltip to explain the circle if a user hovers over it

To test:

• Go to an MX proposal (eg /dc/visit/mx37045-1) and then click the calendar link at the top left. As staff you should see lots of visits for the mx village, check a coloured circle appears next to each, and a tooltip appears if you hover over it. Check there are some green, yellow and black.
• Go to the /visits page, check there is an ERA column with the same circles and tooltip.
• Go to proposal mx18802 and check the visits list, this proposal has High risk sessions from May 2018, so should have red circles.

[NKatti2011]

LGTM