[LTC] Add c10::string_view support to code-gen + code-gen div (#67044)
Summary:
This commit adds support for ops that have string arguments. It also
adds code-gen support for the div op to test the implementation, as
well as code-gen support for the ops that depend on div:
kl_div_backward and embedding_dense_backward.
Test Plan:
test/cpp/build/test_ptltc --gtest_filter=AtenLtcTsTensorTest.TestEmbeddingBackward:AtenLtcTsTensorTest.TestKlDivBackward:AtenLtcTsTensorTest.TestDiv*
