Derive config from .nycrc

I'd like to add a `.nycrc.json` in my project root and have `karma-coverage` pick up on it without needing to specify includes or excludes in my `karma.conf.js`

Example config:
```json
{
"include": ["src/**/*.js"],
"exclude": [
"**/*.test.js",
"stories/*",
"test/*"
]
}
```

Additionally, some users will want to specify a `nyc` key in their package.json with value same as above.

Start by inspecting how karma-coverage reads options from karma.conf.js and how its existing tests cover include and exclude handling. Check the project-root .nycrc.json and the package.json nyc key as configuration sources, then verify that both provide the requested values without requiring those options in karma.conf.js.

Written by the indexing model from the issue text.