feat: migrate to v2 utility libraries (STEP-2447)

[Badlazzor]

Summary

• Drop direct v1 go-utils (command, errorutil, log, pathutil, retry) and go-steputils/commandhelper imports from the step.
• Thread a go-utils/v2 log.Logger through runGradleTask, findArtifacts, findDeployPth, createDeployPth, and failf.
• Use v2 command.Factory for the gradle invocation, v2 fileutil.FileManager for artifact copies, and v2 pathutil.PathChecker for existence probes.
• Replace commandhelper.RunAndExportOutput with an inline helper backed by export.Exporter.ExportStringToFileOutputAndReturnLastNLines.
• Inline the 10-attempt / 1s wait retry loop that v1 retry.Times().Wait().Try() provided.
• errors.As(err, *command.ExitStatusError) replaces errorutil.IsExitStatusError.

Parent milestone: STEP-2381
Ticket: STEP-2447

Notes

• v1 go-utils retained as // indirect: the v2 export package still transitively pulls ziputil from v1 go-utils. Direct require block is v2-only.
• v1 go-steputils fully removed from go.mod — nothing depends on it anymore now that commandhelper is gone.
• cmd.PrintableCommandArgs(): v1 exposed a package-level command.PrintableCommandArgs(false, cmdSlice) we could call before building the cmd. v2 exposes it only as a method on the constructed command, so the Donef("$ %s", ...) log line moved to after cmdFactory.Create(...). The output is what the wrap layer actually invokes — arguably more accurate.
• fileutil.CopyFile overwrite semantics: v1 command.CopyFile uses cp -f behind the scenes (always overwrites). Matched with &fileutil.CopyOptions{Overwrite: true}. In practice findDeployPth already avoids collisions.
• wrap.DetectParams.Logger: passing the logger enables optional Debugf on skip paths inside wrap.Detect. No-op unless debug logging is enabled (this step has no verbose flag); kept for symmetry with the v2 pattern.
• No new unit tests (Milestone 6, out of scope). Test_findArtifacts and TestResolveGradlewPath continue to pass.

Test plan

• go build ./... passes (verified locally).
• go test -race ./... passes (verified locally).
• go vet ./... clean (verified locally).
• Grep gate: no direct v1 go-utils / go-steputils imports in step source (verified locally).
• go.mod: v2 libs only in the direct require block; v1 go-utils demoted to // indirect; v1 go-steputils removed.
• Step CI (check, e2e) passes on Bitrise CI.

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