Allow 'Tools' to expose preference options

The current preference dialog is hard wired to display 2 tabs (settings/network), with fixed contents. Issues like #4180 show that there is the use case for extending this scheme.

A possible way would be to have a list on the left-hand side, with each page displayed on the right-hand side. Following this pattern (rather than adding more tabs) would allow easier runtime extension of the list.

Compatibility with existing tools would be preserved with the creation of a `Tools2` interface or a separate `ToolsExt`. Either way, this would expose a `PreferenceDialogPanel getToolPreferencesPanel()` method.

Start by locating the preference dialog and the existing Tools interface, then read issue #4180 for the motivating extension case. Decide how the preference pages should be represented and how existing tools remain compatible through Tools2 or ToolsExt. Done means tools can expose preference panels while the current settings and network preferences still work.

Written by the indexing model from the issue text.