[WIP] Improve support for inline equations in ep_mathjax plugin

[Copilot]

Thanks for asking me to work on this. I will get started on it and keep this PR's description up to date as I form a plan and make progress.

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This section details on the original issue you should resolve

<issue_title>Can we get the improvement on maths equation support(ep_mathjax plugin) in etherpad-lite?</issue_title>
<issue_description>I am writing a research paper using etherpad-lite for collaboration with my fellow authors. I am familiar with most of the code base of etherpad-lite and used most of its plugins.
I found ep_mathjax plugin which provides equation facility to be not of much use for writing my research paper. ep_mathjax forms images from the latex and paste it on the editor. However we can only put equations at the starting of the line. I mean we cannot provide inline equation in the text like google docs. But may be Google docs might be using different approach for collaboration and not like etherpad where we use magic-dom ids to represent each line on the editor.

Can we here get the better approach to incorporate equations in the etherpad editor so it looks more natural? Right now Image integration for equations does not look to be much neat.

There are two features which I think should be there -

1. Inline equation support
2. Resizing of equation image

Also I was bugged that is image the only solution for equation? Also right now that * which is inserted for every image is also a problem. Sometimes that * mark becomes visible in the text editor.

Thanks
</issue_description>

Comments on the Issue (you are @copilot in this section)

@JohnMcLear Thanks for filing this in the right place @akshat-g

It's on my todo list but as it's enhancement request it's very close to the bottom.

The two ways to make me focus time / effort on it are to either a) do more open source contributions of your own or b) fund my work.

@JohnMcLear RE funding, you can email me for details.

The * is required. We're not trying to replicate Google Docs.

@JohnMcLear It's one of those where it's useful to have but just not within scope of my time to spend on this project Vs core parts of Etherpad ;\