RTL: Flip some dashicons that have directionality

[yoavf]

Description

• editor-outdent, editor-indent, list-view, and editor-ul can and should be flipped in RTL.
• editor-ol (not taken care of yet) needs an RTL version: RTL version needed for editor-ol dashicons#250

How Has This Been Tested?

Manual testing in LTR and RTL mode

Screenshots (jpeg or gifs if applicable):

Before:

After

Types of changes

CSS that will affect the RTL version, and will flip the icons.

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows has proper inline documentation.

[mtias]

this should probably go in a dashicons scss: https://github.com/WordPress/gutenberg/tree/master/components/dashicon

[aduth]

This file is generated, so this import would be overwritten next time the Dashicons is updated. It seems like the RTL flipping could be valuable to have in the base Dashicons repository, but in keeping it generic we'd not want to assume the presence of an .rtl body class. Would it be reasonable to detect RTL from JavaScript inside the component class and apply an inline style?

https://github.com/WordPress/dashicons/blob/master/sources/react/index-header.jsx
https://github.com/WordPress/dashicons/blob/master/sources/react/index-footer.jsx

[aduth]

Mixed whitespace, tabs and spaces.

[gziolo]

@yoavf do you plan to finish this PR or should someone else take it over?

[azaozz]

May be just me but... looks odd with the numbered list icon in LTR and the bulleted one in RTL. Can we use "proper" RTL icons there? Then we only will need to swap the icons in the CSS, not "flip" them.

[aduth]

Closing as stale without response.