Add input with tooltip

[Shadowere]

#1087 Adds input with tooltip

• Adds tooltips to input;
• Adds input with tooltip to demo;
• Adds tests for input with tooltip;

[miguelcobain]

All of this would be solved if we had named blocks instead of a single block. This way we could customize the label with whatever content we want, including an icon + tooltip.

Since named blocks are not a reality, my suggestion is that we accept a labelComponent argument, which paper-input would render if truthy. Example:

{{paper-input
  labelComponent=(component "tooltip-label" text="myLabel" tooltip="My tooltip")
  value=myValue
  onChange=(action (mut myValue))
}}

In the paper-input.hbs template, we would do something like:

{{#if labelComponent}}
  {{component labelComponent inputElementId=inputElementId required=required}}
{{else if label}}
  <label for={{inputElementId}} class={{if required "md-required"}}>{{label}}</label>
{{/if}}

In this case, you could have your own tooltip-label component in which you could do all sorts of crazy stuff.

I can't merge this PR the way it is now because it's too specific. It assumes that people want an info icon, etc.

Let me know what you think.

[Shadowere]

I agree that providing a custom labelComponent will be cleaner and more versatile. I'll change it up soon enough