Is your feature request related to a problem? Please describe.
Remembering all the various template tags that are available can be difficult. To then find them we have to open a browser and go to the tutorials section and use the following tutorial:

https://mockoon.com/tutorial/dynamic-response-with-templating/

Describe the solution you'd like
I suggest bringing all said template tags and info directly into Mockoon itself. Perhaps there could be a template "Tags" icon/text that once click on opens a sliding sidebar next to the code editor. Said sidebar could be toggled open/closed using this "Tags" button. This sidebar would have a (scrollable) list of all the tags available. When a template tag is clicked it will be added to the cursor point in the editor and then be ready for use.

Describe alternatives you've considered
If not a direct to editor insert method, perhaps a "cheatsheet" list of template tags so that we can copy and paste to the code editor.

Additional context
The following "mockup" is very rudimentary and by no means what I suggest the final solution be once finished but, I hope you're able to see where I'm going with this: