Introduce command line like interface

[martinskuta]

We have seen over the years that the semi-natural interface is causing some troubles, because in the end you have to type the sentance in expected format and somtimes even the .(dot) in the end of a sentace can make it not understandable for the bot.

Suggested API:

Registering reviewers

@review register @Mention1,@mentionn
@review register self (in Teams you cannot mention yourself so we need this to self register)

Print status

@review status

All time stats

@review alltime

Find reviewer

@review findreviewer
@review findreviewer --exclude @Mention1,@mentionn

Assigning/Unassigning review directly

@review addreview @Mention1,@mentionn
@review removereview @Mention1,@mentionn

Status changes

@review makeavailable @Mention1,@mentionn
@review makeavailable self
@review makebusy @Mention1,@mentionn
@review makebusy self
@review suspend @Mention1,@mentionn
@review suspend self

Can/Cannot approve pull requests flag

@review ??? @Mention1,@mentionn

Help

@review help