feat: Implement `azdo pipelines variable-group list` command

[tmeckel]

This issue tracks the implementation of the azdo pipelines variable-group list command.

Command Description

List every variable group defined in a project with optional filtering. The CLI must fetch all pages automatically so that users never have to provide continuation tokens manually.

azdo Command Signature

azdo pipelines variable-group list [ORGANIZATION/]PROJECT [flags]

Flags:

• --name: Wildcard pattern applied to the variable group name (groupName in the SDK).
• --action: Action filter string (e.g., manage, use).
• --top: Server-side page size hint (positive integer).
• --order: asc or desc; map to idAscending / idDescending.
• --max-items: Optional client-side cap on results; stop fetching once reached.
• --continuation-token: Manual pagination token for debugging or partial results.
• --group-type: Filter by variable group type (e.g., AzureKeyVault, Generic).
• --include-details: Include additional details like variables, provider data, and project references. (By default only summary columns are shown.)
• JSON export flags registering the same fields as the show/update commands (id, name, type, description, isShared, authorized, variables, variableGroupProjectReferences, providerData, etc.).

Behavior

• Parse the scope argument using existing helpers so [ORGANIZATION/]PROJECT resolves the default organization when omitted.
• Acquire IO streams, start the progress indicator, and ensure it stops before printing output.
• Build taskagent.GetVariableGroupsArgs with the supplied filters (GroupName, ActionFilter, Top, QueryOrder, ContinuationToken).
• Call a loader helper (e.g., azdo.GetVariableGroups) that mirrors azdo.GetProjects and loops through continuation tokens until the server stops issuing them. This makes --continuation-token unnecessary for end users; the command must return the complete set by default.
• Respect --max-items by truncating the collected slice after pagination completes; log via zap.L().Debug when truncation happens.
• Render default table columns: ID, NAME, TYPE, VARIABLE COUNT, DESCRIPTION. When --include-details is provided, add VARIABLE KEYS, AUTHORIZED, PROJECT REFERENCES, and PROVIDER DATA columns. Mask secret values.
• For JSON export, emit { "variableGroups": [...] } with the view struct used by show, filtering fields according to the --include-details flag unless the user explicitly selects them via --json.
• Validate --top and --max-items are positive integers and return an error for unknown --order or --group-type values.

Supporting Helpers

• Add func GetVariableGroups(ctx context.Context, client taskagent.Client, args taskagent.GetVariableGroupsArgs) ([]taskagent.VariableGroup, string, error) to internal/azdo/loader.go. The helper should:
  • Invoke the client, append Value results when non-nil, and surface the last ContinuationToken for debugging (also returned when the user supplies --continuation-token).
  • Reissue requests with the server ContinuationToken until it is empty.
  • Handle numeric tokens similarly to GetProjects, returning wrapped errors when parsing fails.
• Write focused unit tests for the helper using mocks to cover multi-page responses, token parsing failures, and error propagation.

Command Wiring

• Implement the command in internal/cmd/pipelines/variablegroup/list/list.go with NewCmd(ctx util.CmdContext) *cobra.Command.
• Register it from internal/cmd/pipelines/variablegroup/variablegroup.go so azdo pipelines variable-group list is reachable.
• Regenerate documentation (make docs) after wiring.

SDK / Client Requirements

• Requires the Task Agent client (ClientFactory().TaskAgent(...)) for listing variable groups. If the client is not yet exposed, follow “Handling Missing Azure DevOps SDK Clients” in AGENTS.md.

Tooling & Validation

• Format new Go files with gofmt/goimports.
• Run go build ./cmd/azdo/... (or make lint) to ensure imports and types are correct.
• Add/update hermetic tests using mocks and run go test ./....

Testing

• Unit tests verifying:
  1. Listing with a single page via the loader helper.
  2. Multi-page pagination without user-supplied continuation tokens.
  3. --max-items truncation.
  4. Invalid flag handling (--order, --top, --max-items, --group-type).
  5. JSON export structure.
  6. --include-details output with masked secrets.

References

• Azure CLI implementation: variable_group_list
• Azure DevOps REST API 7.1: List variable groups