text: Title: [BUG]
  Body: On editing source on "text" plugin of cms loses some of the data and changes it to something else.  
  
  ## Steps to reproduce
  
  1.  Create a cms page
  2.  Click on the add plugin button and  add `Text`  plugin. 
  3.  Click on the source button and put the source below 
  
  ```<ul style="color: white;">
  	<li>
  	<h4>
         <a href="https://www.google.com" target="_blank">Google</a> 
         <a class="padding-left-5px" href="https://mail.google.com/" title="Gmail"> <i class="fa fa-envelope" aria-hidden="true"></i></a>
      </h4>
  	</li>
  </ul>
  
  
     ```
  
  ## Expected behaviour
  ![image](https://user-images.githubusercontent.com/79985986/165894654-74734b2a-d411-410c-af65-a8dee265a25a.png)
  
  
  
  ## Actual behaviour
  
  ![image](https://user-images.githubusercontent.com/79985986/165894663-d0e19d77-314e-46dc-ac0c-b2eba3d40686.png)
  
  This works fine and as expected 
   
  Now if we do the above steps and
  
  1.  Click on `Text` plugin again and try to edit it. It removes the font-awesome code which was written earlier . 
  ```  <ul style="color: white;">
  	<li>
  	<h4><a href="https://www.google.com" target="_blank">Google</a> <a class="padding-left-5px" href="https://mail.google.com/" title="Gmail"> </a></h4>
  	</li>
  </ul>
  ``` 
  It looks like this after that. 
  
  Now since the font awesome icon is removed if i save this again.   It becomes something like below 
  ![image](https://user-images.githubusercontent.com/79985986/165895021-b076190a-ec0c-445f-85ad-72353ff433cf.png)
  
  So my question is why the fontawesome code is getting removed. 