refactor(tests/frontends/lean): use consistent name convention for file names

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>

src/tests/frontends/lean/CMakeLists.txt

@@ -1,13 +1,13 @@
-add_executable(lean_frontend_tst lean_frontend.cpp)
+add_executable(lean_frontend_tst frontend.cpp)
 target_link_libraries(lean_frontend_tst ${EXTRA_LIBS})
 add_test(lean_frontend ${CMAKE_CURRENT_BINARY_DIR}/lean_frontend_tst)
-add_executable(lean_scanner lean_scanner.cpp)
+add_executable(lean_scanner scanner.cpp)
 target_link_libraries(lean_scanner ${EXTRA_LIBS})
 add_test(lean_scanner ${CMAKE_CURRENT_BINARY_DIR}/lean_scanner)
-add_executable(lean_parser lean_parser.cpp)
+add_executable(lean_parser parser.cpp)
 target_link_libraries(lean_parser ${EXTRA_LIBS})
 add_test(lean_parser ${CMAKE_CURRENT_BINARY_DIR}/lean_parser)
-add_executable(lean_pp lean_pp.cpp)
+add_executable(lean_pp pp.cpp)
 target_link_libraries(lean_pp ${EXTRA_LIBS})
 add_test(lean_pp ${CMAKE_CURRENT_BINARY_DIR}/lean_pp)
 add_executable(implicit_args implicit_args.cpp)