message: cmake: Add fizzy::fizzy-internal INTERFACE library
  The fizzy::fizzy-internal links fizzy::fizzy library with access to
  internal headers.
diff: @@ -36,3 +36,9 @@ target_sources(
  utf8.hpp
  value.hpp
  )
  +
  +# The fizzy::fizzy-internal links fizzy::fizzy library with access to internal headers.
  +add_library(fizzy-internal INTERFACE)
  +add_library(fizzy::fizzy-internal ALIAS fizzy-internal)
  +target_link_libraries(fizzy-internal INTERFACE fizzy::fizzy)
  +target_include_directories(fizzy-internal INTERFACE ${CMAKE_CURRENT_SOURCE_DIR})
  