Add APIs which can get information about the display and the surface area

getDisplayInfo() can get the display information as follows:
 - width[pixel]
 - height[pixel]
 - width[mm]
 - height[mm]

  NOTE:
    It uses wl_output::geometry() for getting physical width[mm] and height[mm] of the display,
    but the value is different with measured value.

    value from wl_output::geometry(): width:320 height:520
    measured value                  : width:193 height:343

getAreaInfo() can get the information of area drawn by the application as follows:
 - x-coordinate
 - y-coordinate
 - width
 - height

The details are described in doc/ApplicationGuide.md.

Bug-AGL: SPEC-1087

Change-Id: I9e6d64ff04e0845b83c69db374d06af17a6d6b66
Signed-off-by: Yuta Doi <yuta-d@witz-inc.co.jp>