[BUGFIX] Correct `linkText` value in headerLink property

[schloram]

Due to the additional option field = header_link setting the output of linkText value was always something like t3://page?uid=13 for internal links. But it would be better to let typolink always handle the linkText to have it replaced with e.g the page title.

Current:

"headerLink": {
  "href": "/my-page",
  "target": null,
  "class": null,
  "title": null,
  "linkText": "t3://page?uid=13",
  "additionalAttributes": []
}

Fixed:

"headerLink": {
  "href": "/my-page",
  "target": null,
  "class": null,
  "title": null,
  "linkText": "My Page",
  "additionalAttributes": []
}

[coveralls]

Pull Request Test Coverage Report for Build 6785483387

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 63.328%

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Totals
Change from base Build 6772803664:	0.0%
Covered Lines:	822
Relevant Lines:	1298

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💛 - Coveralls

[lukaszuznanski]

@schloram thanks for this PR, I'm merging it into master, could you also provide one for version 3.x? You need to create new branch out of 3.x and create PR to 3.x.

Thanks!

[schloram]

@lukaszuznanski Done. -> https://github.com/TYPO3-Headless/headless/pull/673