Allow to add new typedefs in module API

[Totktonada]

We expose our types using typedefs in the module API.

Recently I got the following on PR tarantool/tarantool#7428:

ERROR: do not add new typedefs
#170: FILE: src/lib/core/decimal.h:97:
+typedef STRUCT_DECIMAL decimal_t;

[locker]

Module API typedefs should start with box_ or tt_ so this was fixed by commit 63cc512.

[Totktonada]

Thank you! It works for me.