change width and height of select content dialog box

fixes CNVS-10042

When adding a new module item to the modules page, the select content
dialog box was much to small. This commit both makes the select content
dialog box larger and allows for the 'height' and 'width' option for
future implemenations. I also added test coverage to ensure options are
being used in the dialog box.

-- Test Plan --
draftstate/non-draftstate
- go to the modules page and click the button to create a new module
  item
- notice that the dialog box that pops up is now much larger that it
  once was, it should be 770px wide and 550px tall.
- also notice that the multi select boxes are full width now and
  margins have been taken away from the left hand side.
- also notice there is appropriate padding around the dialog window

Change-Id: I6e6507c19b3a7a9125cdaab12c1acad83eb62108
Reviewed-on: https://gerrit.instructure.com/32518
Reviewed-by: Jeremy Stanley <jeremy@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: Matt Fairbourn <mfairbourn@instructure.com>
Product-Review: Matt Fairbourn <mfairbourn@instructure.com>