CMake: Build serenity_lib libraries with a custom SONAME

This allows libraries and binaries to explicitly link against
`<library>.so.serenity`, which avoids some confusion if there are other
libraries with the same name, such as OpenSSL's `libcrypto`.

Meta/CMake/utils.cmake

@@ -34,6 +34,7 @@ function(serenity_lib target_name fs_name)
     serenity_install_sources("Userland/Libraries/${target_name}")
     add_library(${target_name} SHARED ${SOURCES} ${GENERATED_SOURCES})
     set_target_properties(${target_name} PROPERTIES EXCLUDE_FROM_ALL TRUE)
+    set_target_properties(${target_name} PROPERTIES VERSION "serenity")
     install(TARGETS ${target_name} DESTINATION usr/lib OPTIONAL)
     set_target_properties(${target_name} PROPERTIES OUTPUT_NAME ${fs_name})
     serenity_generated_sources(${target_name})