Allow configuring "auto_stop_setting" through graphql

What does this MR do and why?

Allow configuring auto_stop_setting through GraphQL.

Configuring it through REST API will be enabled by the another MR: !175940 (merged).

Changelog: added

References

• Part of #428625 (closed).

MR acceptance checklist

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Before	After

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Run GDK and open grapiql (https://gdk.test:3443/-/graphql-explorer)
2. Create environment.

mutation CreateEnvironment($projectPath: ID!, $name: String!, $autoStopSetting: AutoStopSetting) {
  environmentCreate(
    input: { projectPath: $projectPath, name: $name, autoStopSetting: $autoStopSetting }
  ) {
    environment {
      id
      name
      tier
      autoStopSetting
    }
    errors
  }
}

# variable
{
  "projectPath": "root/auto-stop-setting",
  "name": "staging3",
  "autoStopSetting": "WITH_ACTION"
}

3. Update it

mutation UpdateAutoStopSetting($environmentId: EnvironmentID!, $autoStopSetting: AutoStopSetting!) {
  environmentUpdate(input: { id: $environmentId, autoStopSetting: $autoStopSetting }) {
    environment {
      id
      autoStopSetting
    }
    errors
  }
}

# variable
{
  "environmentId": "gid://gitlab/Environment/51",
  "autoStopSetting": "ALWAYS"
}

4. Get it

query Env {
  project(fullPath:"root/auto-stop-setting") {
    environment(name: "staging3") {
          id
          tier
          autoStopSetting
    }
  }  
}

response:

{
  "data": {
    "project": {
      "environment": {
        "id": "gid://gitlab/Environment/51",
        "tier": "STAGING",
        "autoStopSetting": "ALWAYS"
      }
    }
  },
  "correlationId": "01JFCBD2DCPEYA7AR5GV2WTKRQ"
}