user32/tests: Added tests for DrawIcon and DrawIconEx (try 9)

[Joel Holdsworth]

Removed 16 and 24 bit tests. The tests only tests against 32-bit dib
sections. The 16-bit tests are too variable across different platforms,
and and the 24 bit results are identical to the 32 bit results.

Tested against: 98 (4-bit, 8-bit, 16-bit, 24-bit, 32-bit), WinNT 4.0
(8-bit, 16-bit, 24-bit, 32-bit) 2000 (8-bit, 16-bit, 24-bit, 32-bit), XP
(16-bit, 24-bit, 32-bit) and unpatched Wine