Twenty Seventeen: Add gradient background options that fit the theme color scheme

[ianbelanger]

Now that we have the option for certain blocks to have gradient backgrounds, we need to add gradient background options to the theme that fit the themes color scheme.

Added some support for gradient backgrounds on editor blocks

Trac ticket: https://core.trac.wordpress.org/ticket/49756

[tomroyer]

Simple-2017-gradients-in-editor

[tomroyer]

I've submitted a pull request using my GitHub account (@PerpendicularCure). This is my first submitted patch. Please let me know if there's anything else expected, or if you have feedback.

[karmatosed]

For now, default themes are being focused on for bugs not enhancements and this means adding new styling isn't something to look at. This also combines with the fact that as the years have passed a recommended way of adding gradients would be through a theme.json file. All of this leads me to recommend that we close this ticket, so I am going to add the keyword 'close' for now.

Thank you for your collaborations on this and if you do wish to add feedback there is absolutely space for that still. The idea is that we could always come back to this at a later point when we have an approach for older default themes that might involve theme.json's even - it's not decided yet.

[sabernhardt]

I am going to close this. It was discussed in Slack, along with other tickets around gradients, and these were left them open for a few days with the 'close' keyword for feedback.

Thank you everyone for your collaboration.