Add flag for autoplanning on draft PR

[cket]

Adds the 'plan-drafts' flag to resolve #1007

[codecov]

Codecov Report

Merging #1008 into master will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #1008   +/-   ##
=======================================
  Coverage   71.98%   71.98%           
=======================================
  Files          65       65           
  Lines        5411     5412    +1     
=======================================
+ Hits         3895     3896    +1     
  Misses       1210     1210           
  Partials      306      306           

Impacted Files	Coverage Δ
cmd/server.go	79.72% <ø> (ø)
server/user_config.go	100.00% <ø> (ø)
server/events/event_parser.go	86.09% <100.00%> (ø)
server/server.go	63.77% <100.00%> (+0.10%)	⬆️

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[lkysow]

Closed in #1053. Thanks!