VAULT-33074: add github sub-command to pipeline (#29403)

* VAULT-33074: add `github` sub-command to `pipeline`

Investigating test workflow failures is common task that engineers on the
sustaining rotation perform. This task often requires quite a bit of
manual labor by manually inspecting all failed/cancelled workflows in
the Github UI on per repo/branch/workflow basis and performing root cause
analysis.

As we work to improve our pipeline discoverability this PR adds a new `github`
sub-command to the `pipeline` utility that allows querying for such workflows
and returning either machine readable or human readable summaries in a single
place. Eventually we plan to automate sending a summary of this data to
an OTEL collector automatically but for now sustaining engineers can
utilize it to query for workflows with lots of various criteria.

A common pattern for investigating build/enos test failure workflows would be:
```shell
export GITHUB_TOKEN="YOUR_TOKEN"
go run -race ./tools/pipeline/... github list-workflow-runs -o hashicorp -r vault -d '2025-01-13..2025-01-23' --branch main --status failure build
```

This will list `build` workflow runs in `hashicorp/vault` repo for the
`main` branch with the `status` or `conclusion` of `failure` within the date
range of `2025-01-13..2025-01-23`.

A sustaining engineer will likely do this for both `vault` and
`vault-enterprise` repositories along with `enos-release-testing-oss` and
`enos-release-testing-ent` workflows in addition to `build` in order to
get a full picture of the last weeks failures.

You can also use this utility to summarize workflows based on other
statuses, branches, HEAD SHA's, event triggers, github actors, etc. For
a full list of filter arguments you can pass `-h` to the sub-command.

> [!CAUTION]
> Be careful not to run this without setting strict filter arguments.
> Failing to do so could result in trying to summarize way too many
> workflows resulting in your API token being disabled for an hour.

Signed-off-by: Ryan Cragun <me@ryan.ec>

tools/pipeline/internal/cmd/github.go

@@ -0,0 +1,26 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: BUSL-1.1
+
+package cmd
+
+import "github.com/spf13/cobra"
+
+type githubCommandFlags struct {
+	Format string `json:"format,omitempty"`
+}
+
+var githubCmdFlags = &githubCommandFlags{}
+
+func newGithubCmd() *cobra.Command {
+	github := &cobra.Command{
+		Use:   "github",
+		Short: "Github commands",
+		Long:  "Github commands",
+	}
+
+	github.PersistentFlags().StringVarP(&githubCmdFlags.Format, "format", "f", "table", "The output format. Can be 'json' or 'table'")
+
+	github.AddCommand(newGithubListRunCmd())
+
+	return github
+}