Catalyst Plugin: attribute names aren't dasherised

[keithamus]

Checklist

• Did you run the analyzer with the --dev flag to get more information?
• Did you create a minimal reproduction in the playground?

Playground link

Catalyst attributes are dasherised when serialised to HTML, which the Catalyst plugin does not quite properly reflect.

Expected behavior

The following code:

import { controller, attr } from '@github/catalyst'

@controller
class HelloWorldElement extends HTMLElement {
  @attr fooBar = 'hello'
}

Would result in an attribute of data-foo-bar in Catalyst 1.x and an attribute of foo-bar in 2.x and so the attributes json should be:

          "attributes": [
            {
              "name": "data-foo-bar", // just `foo-bar` in v2
              "type": {
                "text": "string"
              },
              "default": "'hello'",
              "fieldName": "fooBar"
            }
          ],

Actual behavior

The generated manifest has the following:

          "attributes": [
            {
              "name": "fooBar",
              "type": {
                "text": "string"
              },
              "default": "'hello'",
              "fieldName": "fooBar"
            }
          ],

[thepassle]

@keithamus Could you take a look at this PR to make sure I got it right? 🙂 Thanks #188