[WIP] Add sticky style attributes for ep_align

[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.

---

This section details on the original issue you should resolve

<issue_title>[FR] works with ep_align</issue_title>
<issue_description>Hey, thanks, this can realy help my users !
Do you think it's easy to sticky other attributs of style ?
Am, and lot of people use https://github.com/ether/ep_align
A sticky use for this one (center, right) can help writting)
. but the problem is not exactely the same has bold/italic
. it's about break lines.
. maybe not possible right now :(

... because am using Etherpad number: 1.9.0
Latest available version: 1.8.18
Git sha: 48381de</issue_description>

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