Remove more of the absl dep 2 of 3

indra/cmake/LLFileSystem.cmake

indra/llcharacter/llcharacter.h

indra/llcharacter/llkeyframemotion.h

indra/llcharacter/llmotioncontroller.h

indra/llcharacter/llpose.h

indra/llcommon/CMakeLists.txt

indra/llcommon/llapr.cpp

indra/llcommon/llapr.h

indra/llcommon/llassettype.cpp

indra/llcommon/llbase64.cpp

indra/llcommon/llbase64.h

indra/llcommon/llerror.cpp

indra/llcommon/llinitparam.h

indra/llcommon/llmetricperformancetester.cpp

indra/llcommon/llmutex.cpp

indra/llcommon/llpounceable.h

indra/llcommon/llsdserialize.h

indra/llcommon/llsingleton.h

indra/llcommon/llstaticstringtable.h

indra/llcommon/llstring.cpp