[Templates] Model template parameters, should have 'required' key

[StanZGenchev]

Describe the bug When you try to generate from model templates, all parameters can be left empty because there is nothing telling us which parameters are required and which are not.

To Reproduce Steps to reproduce the behavior:

1. Make a get request to '/services/v4/js/ide-template-service/api/templates.js'
2. See issue:

   {
   "description":"Application with UI, REST APIs and DAOs",
   "extension":"model",
   "id":"template-application-ui-angular/template/template.js",
   "name":"Application - UI (AngularJS)",
   "parameters":[
     {
        "label":"Extension",
        "name":"extensionName",
        "placeholder":"Extension name"
     }
   ]
   }

Expected behavior 'required' should be added to parameters which are required:

{
   "description":"Application with UI, REST APIs and DAOs",
   "extension":"model",
   "id":"template-application-ui-angular/template/template.js",
   "name":"Application - UI (AngularJS)",
   "parameters":[
      {
         "label":"Extension",
         "required":true,
         "name":"extensionName",
         "placeholder":"Extension name"
      }
   ]
}

Desktop:

• OS: macOS 12.3.1
• Browser: Firefox 101
• Version: Dirigible 6.2.28

[harshit-2004]

I want to work on this issue will you assign it to me.