Dialog, TooltipDialog: extend Form

[bill]

Make TooltipDialog? and Dialog extend dijit.form.Form so that the execute() method gets a JSON-ish object representing the form contents when submit is pressed (and also so eventually the Dialog can have validation). This also eliminates the need to specify pointer to save/cancel button inside the dialog.

[bill]

(In [9768]) Make TooltipDialog? extend Form so that it's easier (for the developer) to submit the dialog and to process it's contents. Still need to convert Dialog and update migration guide. Refs #3844

[bill]

(In [9811]) Convert Dialog to extend Form. Fixes #3844.

[bill]

(In [9814]) Fix dojo in build environment, where templatePath is replaced by templateString, so that it was converting:

templatePath: ... templateString: null,

into

templateString: ..., templateString: null,

Refs #3844

[bill]

(In [9817]) Forgot to update some test files. Refs #3844.