Hide "plan" comments

[lkysow]

Updates #897 with master so it can be merged.

Fixes #721

Read commit by commit. Attempted to isolate changes.
Did not implement this for other VCS's. Github is my primary concern right now.
This will only hide "plan" comments, because IMO "apply" comments are important enough to >have unminimized because they impact actual systems and thus may be useful when people >need to audit changes or figure out what/how things broke.

[codecov]

Codecov Report

Merging #994 into master will decrease coverage by 0.07%.
The diff coverage is 66.66%.

@@            Coverage Diff             @@
##           master     #994      +/-   ##
==========================================
- Coverage   72.03%   71.95%   -0.08%     
==========================================
  Files          65       65              
  Lines        5339     5406      +67     
==========================================
+ Hits         3846     3890      +44     
- Misses       1192     1210      +18     
- Partials      301      306       +5     

Impacted Files	Coverage Δ
cmd/server.go	79.72% <ø> (ø)
server/events/command_runner.go	49.37% <0.00%> (-0.63%)	⬇️
server/events/vcs/azuredevops_client.go	66.50% <0.00%> (-0.67%)	⬇️
server/events/vcs/bitbucketcloud/client.go	46.61% <0.00%> (-0.72%)	⬇️
server/events/vcs/bitbucketserver/client.go	34.88% <0.00%> (-0.42%)	⬇️
server/events/vcs/gitlab_client.go	38.65% <0.00%> (-0.67%)	⬇️
server/events/vcs/not_configured_vcs_client.go	0.00% <0.00%> (ø)
server/events/vcs/proxy.go	0.00% <0.00%> (ø)
server/user_config.go	100.00% <ø> (ø)
server/events/vcs/github_client.go	80.47% <84.90%> (+1.65%)	⬆️
... and 1 more

---

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 1d89710...80347f4. Read the comment docs.

[mwarkentin]

@lkysow I'm trying to figure out how to set a boolean flag like this via environment variable - before I go testing random settings (1, true, etc) maybe there could be some docs added to show how to do this?

Maybe a more generic bit in the "environment variable" section of the config docs would handle it for any boolean flags?

[lkysow]

You can set it to the string false or true, e.g. ATLANTIS_HIDE_PREV_PLAN_COMMENTS=true. Yeah I think adding this to https://www.runatlantis.io/docs/server-configuration.html#environment-variables would be great. PRs welcome please!

[mwarkentin]

@lkysow opened a PR for the docs: #1017