Added pencil icon.

[vershwal]

Fixes #4798.
Hey @bhousel!
I have added a new pencil icon and changed the icon for 'Edit custom background' from magnifying glass to pencil icon.
It was also mentioned in the issue that the text should say "Edit custom background URL template" and not "Edit custom background" but it was not discussed, so should I change the text too?

[bhousel]

Before	After

Thanks @vershwal
It looks ok - can you adjust the width of the button so that it looks a bit more centered?

Also, did you draw it or find it somewhere? Just want to make sure it is license compatible with this project. If there is any doubt, I can just redraw the icon from scratch - this is fine too.

[vershwal]

Hey @bhousel!!
I will adjust the width that is fine. But I didn't draw it from scratch. I found it here and then adjusted the code to fit it in our iD-sprite.src.svg. I was not aware of the licence part. Please check that. And if there is any doubt, I would love to draw it myself. I would have to learn it as this is my first time with SVG drawing, but that would be fun.

[vershwal]

Hey @bhousel!! I have modified the icon. I am sure that this one will be license compatible with this project.
Please check.
Before :

After:

[bhousel]

The new icon looks really good ❤️ Thank you!

[vershwal]

Thank you @bhousel!!