Add code for building and running helm operator binary

[varshaprasad96]

The following changes are made in this PR:
1. Add code for building and running helm operator binary
2. Move pkg/internal/controllerutil out of internal/ dir
3. Add separate helpers to read watches.yaml file for helm operator
4. Move diff.go and types.go from pkg/internal to internal/

[coveralls]

Pull Request Test Coverage Report for Build 1408668137

• 173 of 1021 (16.94%) changed or added relevant lines in 9 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-27.4%) to 61.977%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
internal/legacy/helm/types/types.go	31	43	72.09%
internal/legacy/watches/watches.go	68	87	78.16%
internal/legacy/helm/client/client.go	8	93	8.6%
internal/legacy/release/manager_factory.go	0	106	0.0%
internal/legacy/controller/controller.go	7	119	5.88%
internal/legacy/release/manager.go	43	254	16.93%
internal/legacy/controller/reconcile.go	13	316	4.11%

Totals
Change from base Build 1368807916:	-27.4%
Covered Lines:	1674
Relevant Lines:	2701

---

💛 - Coveralls

[joelanford]

As I understand it, all of this code is being moved here so that:

1. We can slim down SDK repo and remove plugin implementations
2. So that we can continue building the existing implementation of the bae image.

Is that right?

I'm wondering if we can dump everything from SDK into internal/legacy/* so that we a) keep it all isolated in one place to make it easier to eventually remove and b) don't pollute the new implementation's libraries.

Lastly, what's the plan for versioning this repo if its going to contain both old and new implementations side by side?

[fabianvf]

I'm wondering if we can dump everything from SDK into internal/legacy/* so that we a) keep it all isolated in one place to make it easier to eventually remove and b) don't pollute the new implementation's libraries.

I think we should probably just drop the old implementation ASAP

[varshaprasad96]

I'm wondering if we can dump everything from SDK into internal/legacy/* so that we a) keep it all isolated in one place to make it easier to eventually remove and b) don't pollute the new implementation's libraries.

I think we should probably just drop the old implementation ASAP

The PR has both the implementations merged. We have both helm and hybrid binaries built here. Since we would still continue to support helm binary, I am not moving this to the legacy/ dir (for now at least). The helpers between helm and hybrid which could be the same are consolidated already.

[varshaprasad96]

@joelanford @fabianvf I have moved helm related code from SDK to internal/legacy. The next follow up step would be to remove this - which (may) require a breaking change in hybrid (or helm).