Add support to specify arbitrary arguments to devappserver

[briandealwis]

Fixes #432

[codecov-io]

Codecov Report

Merging #433 into master will increase coverage by 0.13%.
The diff coverage is 90%.

@@            Coverage Diff             @@
##           master     #433      +/-   ##
==========================================
+ Coverage   65.65%   65.79%   +0.13%     
==========================================
  Files          64       64              
  Lines        1779     1789      +10     
  Branches      277      280       +3     
==========================================
+ Hits         1168     1177       +9     
  Misses        489      489              
- Partials      122      123       +1

Impacted Files	Coverage Δ
...ppengine/cloudsdk/CloudSdkAppEngineDevServer1.java	87.3% <100%> (+0.3%)	⬆️
...ppengine/cloudsdk/CloudSdkAppEngineDevServer2.java	69.35% <100%> (+1.55%)	⬆️
...pengine/api/devserver/DefaultRunConfiguration.java	97.5% <75%> (-1.19%)	⬇️

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[elharo]

What happens if someone passes a known argument as an additional argument? Or if someone passes the same argument in both?

[briandealwis]

The behaviour is up to the devappserver. The additional arguments are appended at the end, before the app directories / service files.

I imagine this will only be used to add items that we don't have any UI to manage.

[briandealwis]

Any concerns @loosebazooka?

[loosebazooka]

Oh oops, I was supposed to look at this. I'll do it right now.

[briandealwis]

ping @loosebazooka ?

[loosebazooka]

Oh sorry again.