feat: introduce endpoint to manage custom assets

[moabu]

Usecase

There should be a clear non filesystem (volume) based solution for possible user customization's such as login pages, CSS, libraries ..etc. Managed clearly by an API endpoint then further optimized by drag and drop in a parent admin ui.

Possible Solutions:

1. Support different cloud buckets such as S3, Google bucket ...etc
2. We use persistence and come up with a method to store the objects efficiently

My personal recommendation is to support this directly in our persistence and remove all file based requirements.

Implementation details:

• Config API Asset endpoint will be saved in DB Store and uploaded to the jetty-server in one go.

• Using Jans Core DBDocumentService for saving the asset in DB.

• Using Jans Core DocumentStoreService for uploading the asset on to jetty-server.

• Sample Client invokes POST endpoint jans-config-api/api/v1/jans-assets/upload endpoint and provides the asset as well as asset-metada

• API does two thing

  • Call to DBDocumentService to save asset in DB.
  • Call to `DocumentStoreService.saveDocumentStream() to upload asset on jetty-server.

• Logic regarding the asset-type and the directory where asset is uploaded on jetty-server is found in issue Issue#8406

• Swagger Spec link

• Child issue 8406

• Discussion chat [thread] (https://chat.gluu.org/group/service_config_api?msg=rYXXDq4ihP92W67Ng) and (https://chat.gluu.org/group/service_admin_ui?msg=2pQpLnd8zhtm6Bvji)

[jgomer2001]

Potentially related
GluuFederation/oxCore#223
GluuFederation/oxCore#188
#2506

[nynymike]

What should we call this endpoint? /agama-assets ?

[jgomer2001]

I'd say /jans-assets because it applies to several projects

[pujavs]

Requirement breakdown:

1. Centrally managing assets(html,css,js,lib, etc) and leveraging existing DocumentStore for the same.
2. Managing assets(html,css,js,lib, etc) in jetty classpath will require to use Jetty API.

[ossdhaval]

@pujavs It looks like this change may require a documentation update as well. Please evaluate the documentation aspect and make the change along with the code change within this PR itself.

[pujavs]

Implemented change via PR 8096