orgmode: add \\ (line break) support

### ⚠️ This issue respects the following points: ⚠️

- [x] This is a **enhancement/feature request**. Not a [bug or question](https://github.com/gsantner/markor/issues/new/choose).
- [x] The topic is **not** already reported at [Issues](https://github.com/gsantner/markor/issues?q=#js-issues-search). _(I've searched it)_.
- [x] Markor **is** up to date. See [Releases](https://github.com/gsantner/markor/tags) for the latest version. Updates are available from [F-Droid](https://f-droid.org/en/packages/net.gsantner.markor/) and GitHub.
- [x] The wanted feature/enhancement is not present in the latest development version (git master). (Please [download](https://nightly.link/gsantner/markor/workflows/build-android-project/master) and try the test version of Markor, named **Marder**. Don't worry; Markor and Marder appear as completely separate applications. You can install both side-by-side, and Markor's settings are not touched. If your desired feature is present, you don't need to open this issue. The change will be part of the next Markor update.)

### Description

Orgmode: add \\\ (line break) support.

https://orgmode.org/guide/Paragraphs.html

### Information

Android version: 13
Device: Ulefone Armor 21
App Version: 2.15.2

### Source

F-Droid

### Format / File type

Something else (-> Additional info)

### Additional info / Log

```shell
orgmode
```

Start by locating Markor's existing orgmode parsing or rendering entry point and compare it with the Org-mode Paragraphs documentation linked in the issue. Implement support for the requested \\ line break behavior and verify that an orgmode document displays it correctly on Android.

Written by the indexing model from the issue text.