[BEAM-7154] Updating Go SDK errors (Part 2)

[youngoli]

Updating standard Go error functionality (errors.New and fmt.Errorf) to use the newly added Beam "errors" package. This PR covers the following subdirectories under sdks/go/pkg/beam: io, options, provision, and runners.

I tried to keep the actual changes as straightforward as possible:

1. If a call isn't wrapping another error, replace it with New or Errorf. This should be functionally identical.
2. If a call is wrapping another error, replace it with either Wrap or WithContext using my best judgement. I generally used Wrap when the wrapped error originates from third-party code (i.e. any non-Beam package), and I tried to use WithContext otherwise.
3. WithContext messages make the most sense in present tense (e.g. "doing foo", "reading bar"). This means I had to adjust some messages slightly, as little as I could without losing any useful information.

Only PR left after this is for the core subdirectory. That one might be a bit large so I wanted to separate it.

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Post-Commit Tests Status (on master branch)

Lang	SDK	Apex	Dataflow	Flink	Gearpump	Samza	Spark
Go		---	---	---	---	---	---
Java
Python		---			---	---	---

Pre-Commit Tests Status (on master branch)

---	Java	Python	Go	Website
Non-portable
Portable	---		---	---

See .test-infra/jenkins/README for trigger phrase, status and link of all Jenkins jobs.

[youngoli]

R: @lostluck

[lostluck]

Mostly LGTM, but we must fix the pre-commit first:

16:34:36 > Task :beam-sdks-go:goTest FAILED
16:34:37 # github.com/apache/beam/sdks/go/pkg/beam/runners/direct
16:34:37 .gogradle/project_gopath/src/github.com/apache/beam/sdks/go/pkg/beam/runners/direct/direct.go:22:2: imported and not used: "fmt"
16:34:37 # github.com/apache/beam/sdks/go/pkg/beam/runners/universal/runnerlib
16:34:37 .gogradle/project_gopath/src/github.com/apache/beam/sdks/go/pkg/beam/runners/universal/runnerlib/execute.go:20:2: imported and not used: "fmt"
16:34:37 .gogradle/project_gopath/src/github.com/apache/beam/sdks/go/pkg/beam/runners/universal/runnerlib/stage.go:20:2: imported and not used: "fmt"

[youngoli]

Strange, I ran goTest on my machine and it didn't catch any errors. I wonder if there's something different between my local environment and the Jenkins environment.

Anyway, fixed those so it should work now hopefully.

[lostluck]

That's almost certainly the case, given the whole GoGradle, Versioning, Etc. situation the SDK is in. I do not recommend testing with the gradle commands locally under the vast majority of cases.

go test ./... should cover everything, but otherwise go build ./... would certainly catch it.

[youngoli]

@aaltay for merge.