Fix long support forum title styling

[jonoaldersonwp]

Particularly long and unbroken thread headings, like on ​https://wordpress.org/support/topic/declaration-of-axiom_plugin_updaterdownload_packagepackage/, bleed outside of the container and viewport on mobile devices.

This is a UI problem, and it negatively impacts our SEO.

This can be easily fixed by adding the following CSS:

.bbpress h1.page-title {
  word-break: break-word;
}

[dd32]

In 9977:

Support: Break long support titles to prevent overflowing container.

Props jonoaldersonwp.
Fixes #5268.