Look up correct MPs

[vteague]

At the moment, even after choosing (random) electorates, it displays a hardcoded list of 'My MPs'.

1. Delete the 'TestCurrentMPs' element from ReadingContext.cs: https://github.com/RightToAskOrg/righttoask-ui-mockup/blob/main/PassingData/ReadingContext.cs
2. In IndividualParticipant.cs,
   https://github.com/RightToAskOrg/righttoask-ui-mockup/blob/main/PassingData/Models/IndividualParticipant.cs, add the corresponding MPs to the list MyMPs whenever something about the participant's electorates is updated - you'll see TODOs in the IndividualParticipant.cs file. This can be done by searching
   BackgroundElectorateAndMPData.AllMPs for those in which the chamber and electorate both match.

For example, if an IndividualParticipant's Vic Legislative Council electorate is updated to "Northern Metropolitan", we'll search through AllMPs for those matching both
ChamberSeatedIn = Vic_Legislative_Council
and
ElectorateRepresenting = "Northern Metropolitan"

3. In SecondPage.xaml.cs https://github.com/RightToAskOrg/righttoask-ui-mockup/blob/main/PassingData/SecondPage.xaml.cs, lines 97 and 113, when we launch the page of 'myMPs', use your newly-correct IndividualParticipant.MyMPs list, instead of the Test default now there.

(Note: electorates are chosen randomly at the moment, unless the person specifies them, but that's a separate issue. Also note only Vic has the electorates loaded, so that's the only one that can work atm.)