[Refactor] Move gRPC and HTTP server logic out of event package

[nkubala]

This moves the server creation logic out of the event package. No functional change.

[codecov-io]

Codecov Report

Merging #2199 into master will increase coverage by 0.08%.
The diff coverage is 46.29%.

@@            Coverage Diff             @@
##           master    #2199      +/-   ##
==========================================
+ Coverage   57.88%   57.96%   +0.08%     
==========================================
  Files         187      188       +1     
  Lines        7903     7911       +8     
==========================================
+ Hits         4575     4586      +11     
- Misses       2915     2916       +1     
+ Partials      413      409       -4

Impacted Files	Coverage Δ
pkg/skaffold/server/endpoints.go	0% <0%> (ø)
pkg/skaffold/event/event.go	89.65% <10%> (-1.96%)	⬇️
pkg/skaffold/server/server.go	51.66% <64.7%> (ø)
pkg/skaffold/runner/runner.go	69.1% <66.66%> (+0.25%)	⬆️
pkg/skaffold/util/port.go	92.59% <0%> (+7.4%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 45dcebd...821de0d. Read the comment docs.

[balopat]

LGTM