Add display of MLA details

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The council version of this was a mess and this continues to be. Perhaps the best approach here is to have this importable via a <script> with various configuration options? 🤔

I’m opening this PR to gather feedback/refine the implementation before next week’s campaign.

• [ ] determine whether form letter is a thing
• [ ] different letters for councillors vs MLAs?
• [ ] should councillors even show?
• [ ] allow showing council only vs council and MB, etc
• [ ] extract letter somehow so this doesn’t change the December “Our city is unwell” iteration

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It’s possible to stuff this all into a post or page instead of altering the theme… I don’t love that approach because it relies on people not changing the user-editable Javascript. Ultimately something like an embeddable widget might work better. But it appears this isn’t going to be used regardless, so I’m closing.