messaging_service.cc depends on idl, but many source files in
scylla-main do no depend on idl, so let's
* move "message/*" into its own directory and add an inter-library
dependency between it and the "idl" library.
* rename the target of "message" under test/manual to "message_test"
to avoid the name collision
this should address the compilation failure of
```
FAILED: CMakeFiles/scylla-main.dir/message/messaging_service.cc.o
/usr/bin/clang++ -DBOOST_NO_CXX98_FUNCTION_BASE -DDEBUG -DDEBUG_LSA_SANITIZER -DFMT_DEPRECATED_OSTREAM -DFMT_SHARED -DSANITIZE -DSCYLLA_BUILD_MODE=debug -DSCYLLA_ENABLE_ERROR_INJECTION -DSEASTAR_API_LEVEL=7 -DSEASTAR_BROKEN_SOURCE_LOCATION -DSEASTAR_DEBUG -DSEASTAR_DEBUG_SHARED_PTR -DSEASTAR_DEFAULT_ALLOCATOR -DSEASTAR_LOGGER_TYPE_STDOUT -DSEASTAR_SCHEDULING_GROUPS_COUNT=16 -DSEASTAR_SHUFFLE_TASK_QUEUE -DSEASTAR_SSTRING -DSEASTAR_TYPE_ERASE_MORE -DXXH_PRIVATE_API -I/home/kefu/dev/scylladb -I/home/kefu/dev/scylladb/build/cmake/gen -I/home/kefu/dev/scylladb/seastar/include -I/home/kefu/dev/scylladb/build/cmake/seastar/gen/include -Wall -Werror -Wextra -Wno-error=deprecated-declarations -Wimplicit-fallthrough -Wno-c++11-narrowing -Wno-mismatched-tags -Wno-overloaded-virtual -Wno-unsupported-friend -Wno-unused-parameter -Wno-missing-field-initializers -Wno-deprecated-copy -Wno-ignored-qualifiers -march=westmere -Og -g -gz -std=gnu++20 -fvisibility=hidden -U_FORTIFY_SOURCE -Wno-error=unused-result "-Wno-error=#warnings" -fstack-clash-protection -fsanitize=address -fsanitize=undefined -fno-sanitize=vptr -MD -MT CMakeFiles/scylla-main.dir/message/messaging_service.cc.o -MF CMakeFiles/scylla-main.dir/message/messaging_service.cc.o.d -o CMakeFiles/scylla-main.dir/message/messaging_service.cc.o -c /home/kefu/dev/scylladb/message/messaging_service.cc
/home/kefu/dev/scylladb/message/messaging_service.cc:81:10: fatal error: 'idl/join_node.dist.hh' file not found
^~~~~~~~~~~~~~~~~~~~~~~
```
where the compiler failed to find the included `idl/join_node.dist.hh`,
which is exposed by the idl library as part of its public interface.
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Closesscylladb/scylladb#15657
a6e68d8309