Add component print styles

[andysellick]

What

We seem to be missing some print stylesheets for some components, where print styles would be sensible. This PR adds some.

Why

People print pages on GOV.UK.

Visual Changes

Screenshots are a bit pointless because most of these changes involve hiding things, but here's a summary.

• attachment: hide the icon (not sure about this one, should we hide the entire component?)
• back link: hide completely
• button: make all buttons look the same (and like buttons, see below)
• textarea: general tidy (see below)
• layout footer: hide everything but the OGL and copyright lines
• layout header: minor change, hide the 'menu' button
• metadata: hide toggle and show all updates links
• search component: hide completely when printed
• skip link: hide it
• subscription links: hide them
• translation nav: hide them

Things I've not added print styles for:

• I was originally going to hide all form elements (particularly the file upload component) but then realised people might actually want to print a form so they can see what fields they need so decided it was better to leave them all visible
• I wanted to add print styles for the details component (the contents of a collapsed one are not shown in print) but apparently this isn't as simple as it might sound, so I've not done that for now
• in theory if a modal dialog is open and someone prints the page it should be visible but as I don't think this is being used on public GOV.UK I don't think it's important right now
• I assumed next and previous navigation wouldn't be needed when printed but it can contain information about the following and preceding pages, so I've left it visible
• I wanted to hide the tabs part of the tabs component (but leave the content visible) but for some reason I can't fathom that caused a test to fail. I wasn't 100% sure about the change anyway, so I've not gone ahead with it for now

Screenshots

Component	Before	After
Button
Textarea

View Changes

https://govuk-publishing-compo-pr-1164.herokuapp.com/component-guide

This PR is related to alphagov/govuk-frontend#573

[injms]

Is is worth adding in a style to add the address to links?

a:link:after,
a:visited:after {
  content: " (" attr(href) ") ";
  font-size: 90%;
}

Source: Improving Link Display for Print

[andysellick]

@injms I believe that's already implemented by static - it happens on the live site.

[injms]

Do you think it's worth putting the '23 characters too many' message below the textarea to mirror 'X words remaining':

[injms]

Small suggestion for the character count component - but other than that tiny thing I think this looks a great improvement.