Create text message system

[kanerogers]

Requirements

• Visible "Phone" UI on right side of screen (1 3rd horizontal width)
• Text message boxes appear
• Text messages contain visible text
• Many text messages can appear
• [POLISH] Player can scroll through messages (?) #15

[pwc]

See #12

Still to do on this:

• Don’t create bevy entites for the missing messages
• Animate as new messages appear
• Play sound as new text messages appear

Propose we leave scrolling as an extension feature.

Once the graphics are done, propose we create a new issue to track issues around the game logic for generating text messages.

cc @kanerogers

[kanerogers]

@pwc I'd say let's close this off for now (eg. we have created the system already) and create sub issues for the other tasks (eg. scrolling, sounds, animation, etc.)