Respect default extension setting in direct editing

[max-nextcloud]

Describe the bug
Given the default extension for text is set to 'txt'
when creating a text document in the ios client
it creates a .md file

To Reproduce
Steps to reproduce the behavior:

1. ./occ config:app:set text default_file_extension --value 'txt'
2. Create a text document from the ios client
3. See .md extension

Expected behavior
The ios client should respect the configured default.

Current Api response

/ocs/v2.php/apps/files/api/v1/directEditing

{
  "textdocument": {
    "id": "textdocument",
    "editor": "text",
    "name": "text document",
    "extension": "md",
    "templates": false,
    "mimetype": "text/markdown"
  }
}