make startNewMeeting, endNewMeeting meeting type specific

[mattkrick]

starting and ending a meeting both have a bunch of logic that is very specific to the meeting type. while down the road we'll have custom meeting types & need a generic startCustomMeeting mutation, for now the logic is a little spaghetti-ish by combining both types in the same mutation.

Acceptance Criteria

• [ ] startCheckinMeeting mutation created
• [ ] startRetrospectiveMeeting mutation created
• [ ] startNewMeeting is deprecated (but not removed, we'll do that later)
• [ ] endCheckinMeeting mutation created
• [ ] endRetrospectiveMeeting mutation created
• [ ] endNewMeeting is deprecated (but not removed, we'll do that later)

Estimate: 6 hours

[abhiaiyer91]

i read the startNewMeeting API and it looks like the only specific logic is around retrospectives.

https://github.com/ParabolInc/parabol/blob/master/packages/server/graphql/mutations/startNewMeeting.ts#L76

Do you want to extract some the shared logic between these mutations?

[mattkrick]

there's a fair bit of stuff for the check-in meetings, too: https://github.com/ParabolInc/parabol/blob/master/packages/server/graphql/mutations/startNewMeeting.ts#L91-L121

the agendaItem stuff should get removed for retrospective meetings, too (that's a current bug).

up to you on how to extract, it's really more art than science