Introduce reporting methods

Nobody has claimed this yet.

**Issue by [insomniacslk](https://github.com/insomniacslk)**
_Thursday Feb 06, 2020 at 14:11 GMT_
_Originally opened as https://github.com/facebookincubator/contest/issues/33_

----

Currently every reporter is responsible for result calculation and delivery of the report. However some tasks are common to many reporters (e.g. sending results over e-mail), and it would be easier on the user if they were supported out of the box. I propose to add a `Methods` section in the reporters that will allow to specify multiple ways of delivering a report.

This should send the JSON report via the specified methods, and also allow (optional) filtering and templating so users can format the report as desired.

```
"Reporting": {
"RunReporters": [
{
"Name": "TargetSuccess",
"Parameters": {
"SuccessExpression": ">80%"
},
"Methods": [
{
"name": "email",
"recipient": "test@example.org"
}
}
]
],
...
}
```

Start by reading the existing reporter configuration and the RunReporters example in this issue. Determine how multiple Methods could deliver the JSON report, including optional filtering and templating, and define what configuration and behavior should count as complete.

Written by the indexing model from the issue text.