Update Linkit module from 6.0.0-beta4 to 6.0.0-rc1 and keep needed patches

Problem/Motivation

Linkit 6.0.0-rc1 was released on: 9 Apr 2023 by: mark_fullmer
https://www.drupal.org/project/linkit/releases/6.0.0-rc1

Proposed resolution

• Change drupal/linkit to 6.0.0-rc1 in the composer.josn file.
• Keep the needed patches for:
  • #3158783: Links around media images break when edited, using Linkit and CKeditor
  • #3201405: Edit internal link and remove the URL breaks layout builder

Remaining tasks

• ✅ File an issue about this project
• ✅ Addition/Change/Update/Fix to this project
• ✅ Testing to ensure no regression
• ➖ Automated unit/functional testing coverage
• ➖ Developer Documentation support on feature change/addition
• ➖ User Guide Documentation support on feature change/addition
• ✅ Accessibility and Readability
• ✅ Code review from 1 Varbase core team member
• ✅ Full testing and approval
• ✅ Credit contributors
• ✅ Review with the product owner
• ✅ Update Release Notes and Update Helper on new feature change/addition
• ✅ Release varbase-9.0.13, varbase_editor-9.0.10

Varbase update type

• ✅ No Update
• ➖ Optional Update
• ➖ Forced Update
• ➖ Forced Update if Unchanged

User interface changes

• N/A

API changes

• N/A

Data model changes

• N/A

Release notes snippet

• Issue #3356225: Updated Linkit module from 6.0.0-beta4 to 6.0.0-rc1 and kept needed patches