Supporting comment headers

[charliesantos]

Current Issue
If we do something like this where there's import right after the @module comment block, this file will be treated as its own module and will ignore @module Voice.

/**
 * @module Voice
 */

import Test from './test';

/**
 * @external
 */
class Device {
  static get testProp(): string {
    return 'my test value';
  }
}

export default Device;

To fix the above issue without updating typedoc npm module, we would need to add dummy comment block before the import statement like below. The reason why this happens is because latest typescript only treats a comment block at the top of the file when there's no code below it. This is a known issue and discussed here TypeStrong#603

/**
 * @module Voice
 */

/**
 * Imports
 * Dummy comment block
 */
import Test from './test';

/**
 * @external
 */
class Device {
  static get testProp(): string {
    return 'my test value';
  }
}

export default Device;

Fix typedoc module
Ideally, this needs to be fixed in the typedoc npm module. There's a recommended fix mentioned in the github issue above (TypeStrong#603) but it requires removing a piece of code, and no-one knows why that code was there. This PR is applying that fix. I didn't see any issues after applying it and this fix will only exists in our fork.