Omit forum link from breadcrumbs for plugin/theme support forums and reviews

[coffee2code]

The "Plugins and Hacks" and "Themes and Templates" forums were hidden in [4583], and while still accessible, we really don't care to direct users to those forums in a general sense. However, the breadcrumbs for plugin/theme support and reviews include links to the those forums. See meta-2486.breadcrumbs.png.

Instead of just removing the forum from the breadcrumbs, we should also prepend the plugin/theme name in the breadcrumbs with "Plugin:" or "Theme:" as appropriate to provide context. See meta-2486.proposed-breadcrumbs.png.

[coffee2code]

Example of current breadcrumbs for a plugin. Links to "Plugins and Hacks" forum.

[coffee2code]

Proposed change to breadcrumbs. No link to forums, and prepend context to plugin/theme name.

[coffee2code]

In 4894:

Support Forums: Omit forum link from breadcrumbs for plugin/theme support forums and reviews

Their general forums are hidden from listings and no longer meant to be directly linked.

Fixes #2486.

[coffee2code]

In 4983:

Support Forums: Also prefix 'Plugin:' or 'Theme:' context to plugin name in breadcrumbs in topic list view.

See #2486.