[jss-isolate] improve API, so plugin could accept multiple configs

[yakhinvadim]

Motivation

See #698 (comment)

TODO

• Decide, should we introduce new 'non-inherited' keyword for reset property
• Decide, how new API should work
• Write tests
• Implement new API
• Update readme

[yakhinvadim]

Right now in order to implement the behavior I described in Motivation section, we'd need to merge two configs:

// 1
jss.use(
  isolate({
    isolate: 'root',
    reset:  'all' // or just 'inherited', because 'non-inherited' part is covered in second config
  })
);

// 2
jss.use(
  isolate({
    reset: 'non-inherited'
  })
);

The first questions is: is it OK to introduce new 'non-inherited' keyword for this use-case?