Is your feature request related to a problem? Please describe.

I'm using non-breaking spaces   to avoid ugly line breaks (e.g. between values and units) and so increase the readability of texts on my site. To see where I have to insert nonbreaking spaces and where I have it already done I have to enable the option "show visible characters" each time I edit or create an article.

Describe the solution you'd like

An option "show invisible characters" in the TinyMCE plugin would be great to set the enabled option (visualchars_default_state: true) as default setting.

Additional context

https://www.tiny.cloud/docs/tinymce/latest/visualchars/