Resolve "[elog_add] wa() output illegible"

Closes #4327

Replaces !6312 (merged)

Requires icat/pyicat-plus!94 (merged) to be deployed on pypi (Edit: deployed on pypi and anaconda)

https://confluence.esrf.fr/display/DATAPOLWK/Electronic+Logbook#Summary

elog_add used to be this (before !6312 (merged))

now it is this (this MR)

So instead of an editable+unformatted message we get a uneditable+formatted message.

In addition this MR allows for message tags and mime type (text/plain by default).

DAU [2]: elog_print("<b>This text is bold</b>", mimetype="text/html")
DAU [3]: elog_print('<h1 style="color:Tomato;">Hello World</h1><p style="color:DodgerBlue;">Lorem ipsum...</p><p style="color:MediumSeaGreen;">Ut wisi enim...</p>', mimetype="text/html")
DAU [4]: