Word2007 Writer : Added support for field REF

[Progi1984]

Description

Word2007 Writer : Added support for field REF

• Add REF options to $fieldsArray in PhpOffice\PhpWord\Element\Field.php
• Added writeRef method to Handle REF options

$textRun->addField('REF', [
      'name' => 'my-bookmark'
  ], [
      'InsertParagraphNumberRelativeContext',
      'CreateHyperLink',
  ]);

Superseeds #2207 by @crystoline

Checklist:

• My CI is 🟢
• I have covered by unit tests my new code (check build/coverage for coverage report)
• I have updated the documentation to describe the changes
• I have updated the changelog

[coveralls]

Changes unknown
when pulling 3e79d6d on pr2207
into ** on master**.

[Progi1984]

Thanks @crystoline for your contribution.