feat: deprecate plugin onInstall return for consistent API

[tgriesser]

Removes the {types: NexusAcceptedTypeDef[]} return value from onInstall plugin api in favor of imperative hasType / addType APIs, for consistency.

[codecov]

Codecov Report

Merging #637 (ab97971) into develop (36503f7) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           develop     #637      +/-   ##
===========================================
- Coverage    92.79%   92.77%   -0.02%     
===========================================
  Files           42       42              
  Lines         2663     2659       -4     
  Branches       579      579              
===========================================
- Hits          2471     2467       -4     
  Misses         192      192              

[jasonkuhrt]

LGTM