Add json-c to msbuild in codebuild CI

[ttjsu-aws]

Add the following to codebuild/common-windows.bat:

1. git clone https://github.com/json-c/json-c.git || goto error
2. mkdir json-c-build
3. cd json-c-build
4. cmake %* -DCMAKE_INSTALL_PREFIX=c:/deps -DCMAKE_BUILD_TYPE="Release" -DCMAKE_TOOLCHAIN_FILE=C:/vcpkg/scripts/buildsystems/vcpkg.cmake ../json-c || goto error
5. msbuild.exe json-c.vcxproj /m /verbosity:normal /p:Configuration=Release || goto error
6. msbuild.exe INSTALL.vcxproj /p:Configuration=Release || goto error
7. Turn on -DAWS_ENC_SDK_KNOWN_GOOD_TESTS=ON flag in cmake

[bdonlan]

I'm going to call this not a release blocker, we don't have any real reason to expect MSVC will behave differently wrt these specific test cases.