Support 'text-indent' CSS in indent plugins

[engineering-this]

Type of report

Feature request

Provide description of the new feature

Currently we don't support CSS property text-indent. It is filtered.

However this CSS allows to indent only first line of text in element. Content copied from Word has this prop for first line indentation, hence this would be required to cover some cases such as comment.

We could even consider adding ruler for easy manipulating of indent and left margin.

Screenshots shows how paragraph with text-indent would look like in our editor.

Notes:

• Extracted from Margin is not preserved when pasting from Word #651.
• Bug: Incomplete CSS margin parsing if "auto" or "0" without unit is used #1330 needs to be fixed first.