Add text selection to ProcessPageEditImageSelect for RTE

[Kiwi Chris]

In the RTE, when inserting a link, there are several input fields that can be used to select a page, including a text input field that will auto-complete with pages on the site.

When inserting an image, there is only an option to navigate the page tree. (equivalent to the second input option 'Select Page...' on the Insert Link screen from the RTE.

When inserting an image from another page buried somewhere in the page tree, if you know the name of the page, it would often be quicker to use an auto-complete text field than 'Select Page...' option.

It would be nice if the image insertion dialog offered the same functionality as the link insertion dialog so that when selecting a page it's possible to choose either to navigate the page tree, or have a text auto-complete field.