Create test_support_chromiumcontent.lib

We use lib.exe to combine all the dependent static libraries into one.
Include test_support_chromiumcontent.lib in the distribution
Fix linker errors with test_support_chromiumcontent.lib

We need to tell the compiler/linker to import symbols that are exported
by chromiumcontent.dll rather than trying to export them again.
Include test support PDBs so we can debug tests