Scrolling to current chapter in mobile TOC

**Context**
We would like the list of the chapters to be scrolled to the current chapter each time the table of contents is opened

**Proposal & Constraints**

The process to find the current chapter when the TOC table is opened is already done. The current chapter element is defined by the class `.current-chapter`. The code to scroll the TOC table to the current chapter should be in the `BookReader.prototype.updateTOCState` function inside `src/js/plugins/plugin.chapters.js`, because it gets called each time the mobile TOC table is opened.
Using something like `.ScrollIntoView()` may not work every time because of conflicts with mmenu. Simpler scrolling methods may cause less unexpected problem.