[aad,avc] unify callbacks to GetAccessToken

The AAD and AVD authentication mechanisms both need an OAuth2 token.
They only differ in the provided arguments, so unify the callbacks into
a single one with variable argument lists.

CMakeLists.txt

@@ -744,6 +744,7 @@ find_feature(PCSC ${PCSC_FEATURE_TYPE} ${PCSC_FEATURE_PURPOSE} ${PCSC_FEATURE_DE
 option(WITH_AAD "Compile with support for Azure AD authentication" ON)
 if (WITH_AAD)
 	find_package(CJSON REQUIRED)
+	include_directories(${CJSON_INCLUDE_DIRS})
 endif()
 
 if (WITH_DSP_FFMPEG OR WITH_VIDEO_FFMPEG OR WITH_FFMPEG)