Add an HTML editor to the admin view

[Schlaumeier5]

• Add a new page: the html editor
• Add a new post request handler to make admins able to modify the html templates
• the html editor should send a request to that handler

[Schlaumeier5]

requires #174

[Sana9058]

@Schlaumeier5 Hi, I’d like to work on this issue if it’s still available. Please let me know if I can take it. Thanks!

[Schlaumeier5]

@Sana9058 sure, if you need something tell me, because this issue is quite complex

[Sana9058]

@Schlaumeier5 Thanks! I’ll start by exploring the current admin views and the related handler logic. I’ll ask if I get stuck on any part.

[Schlaumeier5]

@Sana9058 nice :) you may also have a look at get_paths.json, you have to register a new get path there if you want to add a new page.
Lmk if you need the template system explained, it's custom and maybe a bit ugly (it's the %[...]% stuff)

[Sana9058]

@Schlaumeier5 I’ve opened a PR for this issue implementing the HTML editor page, along with the GET and POST route registration. Please let me know if any changes are needed or if something should be adjusted.