Implement a secret generation function to setup object storage

[blancharda]

Is your feature request related to a problem? Please describe.

As Ezra I want a way to manually setup the S3 configuration directly with the config chart so that I do not need to manage a package out of band in a bundle for this.

Describe the solution you'd like

• Given I have the following for an S3 connection:
  • ENDPOINT
  • ACCESS_KEY
  • ACCESS_KEY_SECRET
  • BUCKET_PREFIX
  • BUCKET_SUFFIX
• When I provide these under the appropriate key (objectStorage.s3) to the config chart
• Then the config chart generates the appropriate gitlab-object-store secret for this service with the appropriate format for an S3 API compliant object storage provider

Describe alternatives you've considered

We could keep the status quo and change Mattermost to not have this pattern but this pattern is a nice to have when you need to manually provide a username / password.

Additional context

• This is similar to the pattern Mattermost uses and should be done similarly from a Helm values perspective: https://github.com/defenseunicorns/uds-package-mattermost/blob/fce7636395d1e3afab5fcf8a502c084bd21a8a83/chart/values.yaml#L12
• Relates to Implement a secret generation function to setup the Database #145
• The current pattern requires duplicating (or sharing) configuration at the bundle level so that the out-of-band secret can set the appropriate bucket name given the prefix/suffix vars.
• Generalizing the helm value to objectStorage at the top level leaves room for other secret implementations for other providers

[Racer159]

Note this should also be documented in the common SWF docs and each depending app's configuration.md