This commit refactors find data dialog to resolve several bugs as well as
similify the code. Now pqFindDataDialog relies on using separate classes for
each of the different components in the dialog making is easier to manage
responsibilities between the various components. Also resolves BUG #14317 and
BUG #14285.

This removes obsolete classes like pqSelectionInspectorPanel, pqQueryDialog and
their UI files as well.

Additionally, this commit fixes pqProxyWidgetDialog to use a container to avoid
proxy widgets not being spaced correctly.

Change-Id: Id51c9f9eceed314f2e9d9823e0523cc1d6037c06