teacher tool: provide a set of premade AI questions (enhancement)

[eanders-ms]

It might help teachers to be able to select from a list of well-formed ready-made questions to ask the AI:

• Are variables used correctly and in a meaningful way?
• Are arrays used properly?
• Are loops used correctly to iterate over arrays?
• Does this project use conditionals properly?
• Does this project illustrate a good understanding of loops?
• etc

[abchatra]

Dupe https://github.com/microsoft/pxt-microbit/issues/5599