[4.x] Fix settings component parameters of menuitems via API

[SniperSister]

Summary of Changes

This PR fixes the creation new menuitems if created via the webservices API. The bug fixed prevented API calls from setting component-specific parameters, as the component parameters were not joined in the form preprocessing.

Testing Instructions

• Create a new menu item for the "feature articles" view of com_content via the webservices API. Set the num_columns parameter of the params array to 5.
• Check the created item in the backend

Actual result BEFORE applying this Pull Request

• "#Columns" field in the Blog Layout tab is empty

Expected result AFTER applying this Pull Request

• "#Columns" field in the Blog Layout tab is set to 5

Example request payload

{
  "access": "1",
  "alias": "",
  "browserNav": "0",
  "component_id": "19",
  "home": "0",
  "language": "*",
  "link": "index.php?option=com_content&view=featured",
  "menutype": "mainmenu",
  "note": "",
  "params": {
    "cancel_redirect_menuitem": "",
    "catid": "",
    "custom_cancel_redirect": "0",
    "enable_category": "0",
    "menu-anchor_css": "",
    "menu-anchor_title": "",
    "menu-meta_description": "",
    "menu-meta_keywords": "",
    "menu_image": "",
    "menu_image_css": "",
    "menu_show": "1",
    "menu_text": "1",
    "page_heading": "",
    "page_title": "",
    "pageclass_sfx": "",
    "redirect_menuitem": "",
    "robots": "",
    "show_page_heading": "",
    "num_columns": 5
  },
  "parent_id": "1",
  "publish_down": "",
  "publish_up": "",
  "published": "1",
  "template_style_id": "0",
  "title": "MyPostTest",
  "toggle_modules_assigned": "1",
  "toggle_modules_published": "1",
  "type": "component"
}

Link to documentations

Please select:

• Documentation link for docs.joomla.org:

• [ x] No documentation changes for docs.joomla.org needed

• Pull Request link for manual.joomla.org:

• [ x] No documentation changes for manual.joomla.org needed

[alikon]

I have tested this item ✅ successfully on 84ac7f8

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[richard67]

I have tested this item ✅ successfully on 84ac7f8

---

_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/44119.}

[richard67]

RTC

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/44119.}

[MacJoom]

Thank you!