Create 'Character Selector' Activity

[tsiemens]

A new fragment that can be reused by various parts of the UI to let user select a subset of characters from a given list. Offering ability to select a variety of characters at once will greatly improve on need to perform import action separately for each desired character

Rough guide to experience:

• Activity is given list of characterIds through intent. (A list of parties (partyIds?) could also be an additional/alternative option, once characters are in parties)
• Activity has two tabs: 'Characters' and 'Parties', listing character names and party names respectively
• Don't display a tab if there are no options provided for it (e.g. no party tab if no provided characters belong to parties)
• Displays a checkbox for each of these character names/party names
• Offer fixed-in-place buttons for 'Ok' and 'Cancel' at bottom of screen
• Offer confirmation prompt for either ok/cancel options
• Pressing 'Ok' confirmation prompts activity to return list of characterIds for all selected characters and all characters belonging to any selected parties
• Has a single character selection mode (will be no party tab)
• Has live(maybe) search field for filtering

[tsiemens]

This is mostly finished at this point. Will close once it has been integrated, and better tested.