Wp-calypso: Focused Launch: "ask for help" block in Summary view

[ciampo]

• [x] On mobile screens, the support link should be at the bottom of the page (non-sticky)

• [x] On desktop screens, the support link should be side-to-side with the _"Launch your site"_ button

• [x] The gray text reads _"Questions? Our experts can assist"_

• [x] The link reads _"Ask a Happiness Engineer"_ and, when clicked, should redirect the user to the /help page

[ciampo]

@ollierozdarz and @razvanpapadopol please take a look at this issue's specs, in case I missed or misunderstood and requirements

[ollierozdarz]

@ciampo Looks good to me.