[FR] Create a Mail Merge

### Description

Add the ability to use an EJS https://ejs.co/ format to create intelligent mail merge-like documents. This will ensure compatibility with Node.js backend servers. The EJS format is quite well-documented and known by many in the IT space.

What we are looking at doing is contributing to the community and adding this functionality to the AppFlowy editor. If someone has started working on something like this or is there, someone we can contact to contribute this functionality, please let me know.

### Impact

This would give AppFlowy the ability to be used in many applications to create emails, PDF documents, and even printable transactions like Invoices. Again, by using EJS we can link our Flutter app with Node in the backend easily.,

### Additional Context

_No response_