Update object storage consolidated configuration for the Google provider

🤔 What does this merge request do and why?

Due to Improve Google Cloud Storage support (&9457 - closed), when object is configured with:

• consolidated form
• provider set to Google

Workhorse has to be configured to build its own object storage client. See this example.

GDK already do this for the two other providers: AWS and Azure. This MR adds support for Google.

Now, the Google provider has 3 ways to be configured:

• Using ADC.
• Pointing to the credentials json file.
• Dumping the contents of the credentials json file in the config file.

We can safely blindly support all 3 in parallel. If workhorse receives all 3 in its config file, it will try them one by one and the first that succeeds will be used. See this function.

⚙ How to set up and validate locally

Have a gdk.yml file with:

object_store:
  enabled: true
  consolidated_form: true
  connection:
    provider: Google
    google_project: "project"
    google_application_default: true
    google_json_key_location: "/dev/null/credentials.json"
    google_json_key_string: |-
      {
        "multi_line": true,
        "credentials": {
          "foo": "bar"
        }
      }

1️⃣ With master

• $ gdk reconfigure
• Check gitlab/workhorse/config.toml, you will get:

[object_storage]
  provider = "Google"

This is not a valid Workhorse configuration and it will 💥 when starting because that's when the object storage provider client is built.

2️⃣ With this MR

• $ gdk reconfigure
• Check gitlab/workhorse/config.toml, you should see that it contains:

[object_storage]
  provider = "Google"



[object_storage.google]
  google_application_default = true
  google_json_key_location = "/dev/null/credentials.json"
  google_json_key_string = '''
{
  "multi_line": true,
  "credentials": {
    "foo": "bar"
  }
}
  '''

🎉

📣 Impacted categories

The following categories relate to this merge request:

• gdk-reliability - e.g. When a GDK action fails to complete.
• gdk-usability - e.g. Improvements or suggestions around how the GDK functions.
• gdk-performance - e.g. When a GDK action is slow or times out.

🏁 Merge request checklist

• This change is backward compatible. If not, please include steps to communicate to our users.
• Tests added for new functionality. If not, please raise an issue to follow-up.
• Documentation added/updated, if needed.
• Announcement added, if change is notable.
• gdk doctor test added, if needed.
• Add the ~highlight label if this MR should be included in the CHANGELOG.md.