Add extra env to helm template

[Utwo]

What this PR does / why we need it:

Provide the ability to add extra env variables to the replicated-sdk deployment.

Steps to reproduce

Add the following snippet to the helm value file.

extraEnv: 
  - name: TEST
    value: 123

Run helm template repli . --dry-run --debug -f values.yaml.tmpl and you should see the value added in the replicated-deployment env.

Does this PR introduce a user-facing change?

A new `extraEnv` attribute was added to the helm values.

Does this PR require documentation?

NONE

[cbodonnell]

Thanks for the contribution, @Utwo! It looks like we may need to pull these changes into a branch to run our tests on them. I can do that and share the PR here.

[Utwo]

Alright, thank you!

[cbodonnell]

Alright, thank you!

#96 Is merged with these changes and will be available in the next release. Thanks again!

[Utwo]

Nice! Do you know when the next release will be available?

[cbodonnell]

Nice! Do you know when the next release will be available?

@Utwo I'll aim to get this released tomorrow for you and will keep you posted.

[Utwo]

Monday is fine, no need to have this over the weekend.

[cbodonnell]

@Utwo FYI - this one is available now in v1.0.0-beta.9. Let us know how it works out for you.