[Socialise] Make People tab more like an address book/directory

[EdNutting]

Is your feature request related to a problem? Please describe.

Finding people who's names don't begin with the letter A takes a stupidly long time!

Describe the solution you'd like

• A quick way to jump to later in the list of people - like a the letter-based indexing of a traditional directory.
• More comprehensive search features - e.g. enhance searching by one or more badges
• The ability to search by "name starting with a letter" rather than the min 3 characters "names containing this string"
• Automatically load more people when scrolling down

Additional context

Feedback from a member of the CLSummit community via their Help Desk. (Thank you!)