Implement sdf/types.h internal unit macros with variadics instead of BOOST_PP_LIST

[nvmkuruc]

Description of Change(s)

By changing _SDF_UNITS to a variadic tuple instead of a BOOST_PP_LIST, several internal macros in pxr/usd/sdf/types.h can be implemented in terms of existing tf/preprocessorUtilsLite.h macros. Removing these macros reduces the project's dependency on several boost preprocessor headers (like boost/preprocessor/list).

This change additionally converts some size macros to constexpr variables and C-style arrays to std::array. The constexpr changes avoids expanding the macro in multiple places and localizes error messages. std::array is preferred per the C++ Core Guidelines (https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#slcon1-prefer-using-stl-array-or-vector-instead-of-a-c-array) and its usage simplified the migration.

Fixes Issue(s)

• I have verified that all unit tests pass with the proposed changes

• I have submitted a signed Contributor License Agreement

[jesschimein]

Filed as internal issue #USD-8587