* Allow only images in modal image uploader.
* Set file path and mime in file selector.
* Refactor WebFile.
* Update get-file-from-path to work with folders; fix file-list component.
* Get rid of File | string for filePath property in components.
* Show instant preview while updating channel thumbnail.
* Fix publish.
* Add jpeg and svg to image filter.
## Issue
Closes 5687: Ensure post mode has no text limit
## Changes
- `type="markdown"` can now have unlimited length if clients don't define `textAreaMaxWidth`.
- The internal default limit of 2000 is narrowed down to `type=textarea`.
