feat(slider): create a CDK slider component

It would be nice to have a CDK slider that allows for more user customization than mat-slider.

Things to support:

• Multiple thumbs (should follow a11y pattern here: http://oaa-accessibility.org/example/32/)
• Provides elements to style for things like thumb, filled track, non-filled track, etc, but leaves that styling up to the user
• Should be able to base mat-slider off of it

[k3rne1pan1c]

Is this feature already available?

[VagrantAI-c]

• STOP - as done in your link: http://oaa-accessibility.org/example/32/
• PUSH - push the other thumb as you drag the other into it.

I wonder if any thumb should be freely dragged from 0 to 100% without bumping into each other (I mean when thumb is blocked for further drag to specified side) and without linking that this one thumb is for left part and another is for right part. Min and max values would be reactively calculated depending on current thumbs positions. It might provide better UX for specified cases depending on user actual needs (just speculating though, I didn’t do any research on this).