Switch Kicad app icon to use trademarked image
# Description
We probably want to use the trademarked image for the app icon:

From Wayne:
> Please keep in mind that the KiCad logo will be used as our trademark identifier so changing it may have legal implications. Personally I would rather we keep the original design since it has been the image that users identify KiCad with.
# KiCad Version
<!-- Copy version information (from main menu Help->About KiCad ->Copy Version Info) and paste it between the triple backticks below to preserve the formatting. -->
```
Application: Pcbnew
Version: (5.99.0-8240-g3fd128a75b-dirty), debug build
Libraries:
wxWidgets 3.0.4
libcurl/7.57.0 OpenSSL/1.0.2n zlib/1.2.11 libidn2/2.0.4 libpsl/0.19.1 (+libidn2/2.0.4)
Platform: macOS Mojave Version 10.14.6 (Build 18G7016), 64 bit, Little endian, wxMac
Build Info:
Date: Jan 8 2021 11:18:06
wxWidgets: 3.0.4 (wchar_t,wx containers,compatible with 2.8)
Boost: 1.72.0
Curl: 7.57.0
ngspice: 26
Compiler: Clang 11.0.0 with C++ ABI 1002
Build settings:
KICAD_SCRIPTING=OFF
KICAD_SCRIPTING_MODULES=OFF
KICAD_SCRIPTING_PYTHON3=OFF
KICAD_SCRIPTING_WXPYTHON=OFF
KICAD_SCRIPTING_WXPYTHON_PHOENIX=OFF
KICAD_SCRIPTING_ACTION_MENU=OFF
KICAD_SPICE=ON
KICAD_STDLIB_DEBUG=OFF
KICAD_STDLIB_LIGHT_DEBUG=OFF
KICAD_SANITIZE=OFF
```
issue