Use correct type name instead of index for TEMPLATE_PRODUCT_TEST_CASE (#1544)

Previously, for a TEMPLATE_PRODUCT_TEST_CASE("Test" ..., T, (P1, P2)),
the generated test case names were

  Test - 0
  Test - 1

With this commit, the correct typename is used:

  Test - T<P1>
  Test - T<P2>

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MSVC needs another indirection to evaluate INTERNAL_CATCH_STRINGIZE
and also inserts a space before theINTERNAL_CATCH_STRINGIZE_WITHOUT_PARENS
parameter, which we can get rid of by pointer arithmetic.