Add AWS::Location::ApiKey

### Name of the resource

Other

### Resource name

AWS::Location::ApiKey

### Description

Add support for resource type AWS::Location::ApiKey.

**Rationale:**
We use AWS Location Services across a large number of clients and we provision ApiKeys for each client for two reasons:

1. Separation of concerns. If a client misbehaves we can disable their ApiKey without affecting others.
2. Each ApiKey can only have 5 trusted referrers and we have 50+ per environment.

All our ApiKeys are identical in their configuration and would be very easily managed via a CloudFormation template.

### Other Details

https://docs.aws.amazon.com/location/latest/APIReference/API_CreateKey.html

Read the issue's AWS::Location::ApiKey requirements and the linked AWS Location CreateKey API reference first. Determine how this repository tracks CloudFormation resource coverage and what validation is required. Done means CloudFormation supports provisioning AWS::Location::ApiKey with the configuration described in the issue.

Written by the indexing model from the issue text.