MXS-1621: Add ALTER TABLE ... [FIRST | AFTER col ] parsing

The parser checks whether the FIRST or AFTER keywords are used and, if
AFTER is used, extracts the relevant column name.

Added a test case that checks that the parsing works and detects the
correct column names.

server/modules/routing/avrorouter/CMakeLists.txt

@@ -6,6 +6,10 @@ if(AVRO_FOUND AND JANSSON_FOUND)
   set_target_properties(avrorouter PROPERTIES LINK_FLAGS -Wl,-z,defs)
   target_link_libraries(avrorouter maxscale-common ${JANSSON_LIBRARIES} ${AVRO_LIBRARIES} maxavro sqlite3 lzma)
   install_module(avrorouter core)
+
+  if (BUILD_TESTS)
+    add_subdirectory(test)
+  endif()
 else()
   message(STATUS "No Avro C or Jansson libraries found, not building avrorouter.")
 endif()