Sensor should be able to create issues that are loaded from external rule engines.
These issues are not associated to a rule declared by the analyzers.
This should be done through a new method in the SensorContext, for example #newExternalRuleIssue. See the existing #newIssue.
These issues need to support the following fields:
- location (including message and file. optionally it can be precise and have secondary locations)
- type: bug, code smell, vulnerability
- remediation cost (optional)