vote: custom headers option support

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Please vote for this feature by using the Github Reactions button and the 👍 reaction. When this feature reaches 10 votes, it will be implemented.

Feature Use Case

Users may need the ability to specify custom request headers frequently enough to warrant a formal option for defining them quickly and easily. At present, custom headers can be defined by following the method described in #36.

Feature Proposal

Proposed headers options property. This property will specify headers in a key-value set from which the server will add headers to every request.

new WebpackPluginServe({
  headers: {
    'X-Superhero': 'batman'
  }
})

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OK. The issue has the 10 👍 required. We'll get to work on adding this.