Fix codemirror options updating.
Fix codemirror options updating.

In #10128, the editor options were consolidated, but an error in the code led to them never being updated when the plugin settings were changed. In particular, https://github.com/jupyterlab/jupyterlab/pull/10128/files#diff-ab6be7bde52236b400a3794134a804439f840f5cf2a9bcb325bbe6f4f0b91823R255 created an editorOptions object which never was updated.

This commit creates an editorOptions object when it needs it from the live global values. This means that, for example, changing the setting for scrollPastEnd will update existing file editors and apply to new file editors.

jupyter/jupyterlab,jupyter/jupyterlab,jupyter/jupyterlab,jupyter/jupyterlab,jupyter/jupyterlab