Adjusting dialog grids areas to better position footers, buttons, and headers #2813 (#2820)
* adjusting grids areas for dialogs to deal with long footers and long buttons
* using grid-column values to position the header when no typeIcon
* improving the header placement in fullscreen takeover
* adding a story for testing and catching anotehr edge case
* Account for all possible grid layouts joining grid areas (#2856)
* adding dialog examples to chromatic to automate testing
* Fix incorrect class when heading and header are two lines
* preventing heading from floating over header
Co-authored-by: Robert Snow <rsnow@adobe.com>
Co-authored-by: Daniel Lu <dl1644@gmail.com>