[APM] Design - General layout updates

[formgeist]

Summary

To better match the general styleguide of K7, I've made some fundamental layout changes to the app. Primarily paneling our graphs and tables and replacing the white background colour. This creates depth and frames each component on the page.

Checklist

Use strikethroughs to remove checklist items you don't feel are applicable to this PR.

• This was checked for cross-browser compatibility, including a check against IE11
• Any text added follows EUI's writing guidelines, uses sentence case text and includes i18n support
• Documentation was added for features that require explanation or tutorials
• Unit or functional tests were updated or added to match the most common scenarios
• This was checked for keyboard-only and screenreader accessibility

For maintainers

• This was checked for breaking API changes and was labeled appropriately
• This includes a feature addition or change that requires a release note and was labeled appropriately

[elasticmachine]

Pinging @elastic/apm-ui

[elasticmachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request

[cchaos]

Woohoo no more white background! Screenshots and less one line of css LGTM!

[sorenlouv]

Awesome job @formgeist!
Are those screenshots really our app and not mocks? Looks great!

[makwarth]

Whoa, this made my day! :) We've been working out of K7 mockups for 18 months, so to see it all come to life now is an amazing milesone. Great work everyone! (I'm on the road so no able to run this locally for review)

[makwarth]

Just had a thought: I'd be cool to blog about the design progress of the APM UI - from its release in 6.1 to now in 7.0. We have release screenshots from each release blog post, so shouldn't take long to put together. It's a great way of showing off the Design team's work, and the pace of the APM product development.
/cc @jamiesmith @nehaduggal @tbragin

[jasonrhodes]

oh thank GOD we got those charts back in the boxes, that's been bothering me since we released metrics! Looks great, nice work 👏

[jamiesmith]

I like it. You could even spice it up with some of the wireframes that you made

[formgeist]

I can put the image content together at the very least and probably right about some of the challenges and decisions made with those first releases.

[tbragin]

@makwarth I added to the observability blogs ideas. We can discuss who is best positioned to write this blog.