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

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>