ENH: Styler accepts css-strings input args as well as list of (attr,value) pairs

[attack68]

Is your feature request related to a problem?

Currently the styler has the ability to set_table_styles provided they are characterised with a css-selector and list of attribute value pairs, e.g.

styler.set_table_styles([{'selector': 'th', 'props': [('color', 'red'), ('font-size', '1em'), ('font-weight',  'bold')]}])

Even the legacy docs describe this as a bit of a pain, and for someone used to css, they will be typically looking for a css-style solution:

styler.set_table_styles([{'selector': 'th', 'props': 'color:red;font-size:1em;font-weight:bold;'}])

Describe the solution you'd like

optionally use the input argument valid CSS format above.

API breaking implications

none if backwards compatible.