Add a new usage to track usages with integrated apps

### Short Description

The BBC intend to integrate BBC Images with a number of applications within the BBC. To help establish on audit trail of where these images have been used, who by and by what integrated app, we require a new usage to be added to the usages service.

### Proposal

We would add a new usage: 'Integration Usage' to the usages service.

This new usage would have the proposed json body:

```
"data":{
"integratedby": string,
"integration tool": string,
"mediaId": string,
"dateAdded": date time
}
```
And the proposed API end point:

```
POST /usages/integration controllers.UsageApi.setIntegrationUsages
```

### Pre-Grid Hour

Our intention would be to dicuss this further during the upcoming grid hour, with our main questions being:
- Does the Guardian have any experience with integration The Grid that could be useful to share?
- Are there any ammendments required to the proposal?
- Could this usage be developed in a way that would make this generic enough that other users of The Grid would also be able to benefit from it?

Start by reviewing the usages service and the proposed UsageApi.setIntegrationUsages endpoint. The grid-hour questions about the schema, genericity, and integration experience need resolution before implementation. Done means the agreed Integration Usage API is implemented with its final request fields and behavior.

Written by the indexing model from the issue text.