Parameterize # of GameServer Creation/Deletion

[nottagg]

Fixes #157

Felt like a pretty similar change to #419, so I figured I would take a look.

• The max number of servers to add/delete are now parameters in gameserverbuild_controller.go
• config.go was created, moving the config struct from main.go to its own file inside controllers
• This allows any controller to now accept the config struct and make use of env variables
• gameserverbuild_controller.go constructor now utilizes the config
• Changing the default values of 20 can be done during deployments via env variables

I did not make these env variables in the makefile. I could refactor the PR to do so if desired, but I figured it would be better to wait on a change fixing the dropped double quotes I faced in #419 . Unlike that one, these wouldn't require an int and string variable so it would be a little prettier. Combining these max add/delete into one variable may also be a refactor to consider. Thanks!

[nottagg]

@microsoft-github-policy-service agree company="Microsoft"

[dgkanatsios]

hey @nottagg, thanks for the PR! A couple of changes and we would be good to go!

[nottagg]

Hey @dgkanatsios,

This is ready for review. I've also updated the original description to better reflect the changes made. I think things should further be refactored to eventually separate the type files (port_registry, config) from the controller folder into their own folder. But I won't include that onto this PR

[dgkanatsios]

while this works, the Config struct defines some default values and it would be great to test them as well. Any chance we can use the same code we have in main.go? Like

cfg := &Config{}
if err := env.Parse(cfg); err != nil {
    log.Fatal(err, "Cannot load configuration from environment variables")
}

[dgkanatsios]

We might need to provide some dummy values for the ones that should not be empty, like THUNDERNETES_INIT_CONTAINER_IMAGE and THUNDERNETES_INIT_CONTAINER_IMAGE_WIN

[nottagg]

Latest commit uses the parse from main.go and filled in some defaults.

[dgkanatsios]

[dgkanatsios]

great job @nottagg, thank you!