Add link to "Create topic" above topic list in support forums

[tobifjellner]

For new users (and not only) it's not always obvious that the form to submit a new topic is located much further down on the page. On a relatively wide screen, there's a sidebar link ready + Create Topic, but on a narrow screen (like mobile) the sidebar is also located much further down the page (when you'd actually need it the most...)

Suggestion:
Add the same link + Create Topic just above the topic list.
And perhaps also on top of every single topic view.

This small change should give us quite a few less "hi-jacked" threads in the forums.

I'll add a home-cooked mockup.

[tobifjellner]

An example what it might be like if we add the link "+ Create Topic" just before the topic list.

[obenland]

In 7450:

Support: Add Create Topic link atop topics list

Hopefully helps avoiding hijacked topics by new users.

Props tobifjellner.
Fixes #3595.

[obenland]

In 7453:

Support: Button styles for Create Topic link

Helps it to stand out a little more.

See ​https://wordpress.slack.com/archives/C02QB8GMM/p1531439297000201
See #3595.

[coffee2code]

In 9463:

Support Forums: Also add 'Create Topic' link above support forums for plugins and themes, and reviews.

Props melchoyce, coffee2code.
See #3595.
Fixes #1977.