osxkeychain: switch to github.com/keybase/go-keychain

[crazy-max]

closes https://github.com/docker/docker-credential-helpers/issues/280

[codecov-commenter]

Codecov Report

Patch coverage: 71.15% and project coverage change: -2.60 :warning:

Comparison is base (83d38ea) 52.74% compared to head (e61a226) 50.15%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #282 +/- ## ========================================== - Coverage 52.74% 50.15% -2.60% ========================================== Files 9 9 Lines 673 642 -31 ========================================== - Hits 355 322 -33 - Misses 271 272 +1 - Partials 47 48 +1 ``` | [Impacted Files](https://app.codecov.io/gh/docker/docker-credential-helpers/pull/282?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=docker) | Coverage Δ | | |---|---|---| | [osxkeychain/osxkeychain.go](https://app.codecov.io/gh/docker/docker-credential-helpers/pull/282?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=docker#diff-b3N4a2V5Y2hhaW4vb3N4a2V5Y2hhaW4uZ28=) | `56.52% <71.15%> (-12.59%)` | :arrow_down: |

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[thaJeztah]

Haven't checked yet, but possibly this also fixes https://github.com/docker/docker-credential-helpers/issues/177

[thaJeztah]

So the only concerns I have is that this

• adds a new dependency (it looks actively maintained, but doesn't have tagged releases yet)
• do we know what the scope is of the dependency? you mentioned secretservice, and it looks indeed that they implemented a package for that as well in https://github.com/keybase/go-keychain/tree/c2ce0606900517e98f5dbfbd7d03f91424bc5867/secretservice
• ^^ that can be both a "positive" (perhaps it's an implementation we could also use), but could also be a "negative" if they start adding <unlimited> other back-ends

In general, I'm wondering if we should start to reorganise this repository into multiple modules, because it's now a "mono-repo" containing both the client / API / library code (client, credentials, registryurl), as well as actual implementations (wincreds, osxkeychain, secretservice, pass), with (possibly) more implementations to be added (see https://github.com/docker/docker-credential-helpers/pull/268, https://github.com/docker/docker-credential-helpers/pull/235)

Some possible approaches;

• make each implementation its own module (which can also be tagged separately)
• somehow refactor the client / API / library code to become its own module (and tag that separately)
• ^^ using vendoring would probably be a bit of a challenge though (vendoring usually would be for binary code, which would now potentially be spread over multiple locations, unless we have a implementation/ or cmd/ directory shared between implementations)

[crazy-max]

• do we know what the scope is of the dependency? you mentioned secretservice, and it looks indeed that they implemented a package for that as well in https://github.com/keybase/go-keychain/tree/c2ce0606900517e98f5dbfbd7d03f91424bc5867/secretservice

• ^^ that can be both a "positive" (perhaps it's an implementation we could also use), but could also be a "negative" if they start adding <unlimited> other back-ends

Added support for secretservice as well: https://github.com/docker/docker-credential-helpers/pull/290