Parser able to read comments/documentation

Known issues: 
 - Android Build process eats comments.
 - Simple implementation without any validation, WIP

This PR is to discuss the issues. Do not merge until resolved.

Problem: If we use the `ValueResourceParser` and parse the processed `values.xml` file, which is generated by the build process, then there are no comments, the get eaten.
Possible solution: we need to parse the untouched xml files (`strings.xml`, ...) to get the comments/documentation...

Original `strings.xml`:

    <resources>
      <!-- This is a comment. Hopefully it makes it to the Javadoc someday! -->
      <string name="simple_test">The {quick} brown {fox} jumps over the {lazy} {dog}.</string>
      <string name="non_matching">A man, a plan, a canal. Panama.</string>
    </resources>

Processed/generated `values.xml`:
    
    <?xml version="1.0" encoding="utf-8"?>
    <resources>

      <!-- From: file:/Users/d/Projects/github/paraphrase/src/test/fixtures/simple/src/main/res/values/strings.xml -->
      <eat-comment />

      <string name="non_matching">A man, a plan, a canal. Panama.</string>
      <string name="simple_test">The {quick} brown {fox} jumps over the {lazy} {dog}.</string>

    </resources>


Additional todos:
`<!-- <string name="disabled_string">...</string> -->` should be ignored and not seen as documentation