Refactor Relocatable Pointer and Relative Pointer

[elfenpiff]

Brief feature description

The relocatable pointer (iceoryx_utils/internal/relocatable_pointer) implementation needs to be cleaned up:

1. add noexcept, const, replace size_t with uint64_t (done in Iox #605 cleanup relocatable ptr #618 except making parameters const)
2. separate implementation and declaration for all classes (Iox #605 cleanup relocatable ptr #618)
3. one class per header file (Iox #605 cleanup relocatable ptr #618)
4. add subnamespace iox::rp where everything is stored (Iox #605 cleanup relocatable ptr #618)
5. restructure the unit tests / add missing tests Moved to Restructure RelativePointer unit tests #1745
6. add doxygen documentation (Iox #605 cleanup relocatable ptr #618)
7. remove includes of base_relative_ptr.hpp & base_relocatable_ptr.hpp
8. consider removing ptr_t and const_ptr_t aliases and use void* directly (see Iox #605 cleanup relocatable ptr #618 (comment))
9. add void* get() noexcept, const void* get() const noexcept, void* getBasePtr() noexcept and const void* getBasePtr() const noexcept to BaseRelativePointer -> Not implemented as SharedPointer uses get() const noexcept
10. consider changing return type of PointerRepository::unregisterPrt() to void (see Iox #605 cleanup relocatable ptr #618 (comment)) - Note: maybe not, it might be useful to have an indication whether the deregistration was successful
11. move duplicated code into a separate method (see Iox #605 cleanup relocatable ptr #618 (comment))
12. rename PointerRepository::registerPtr() methods if both are needed (see Iox #605 cleanup relocatable ptr #618 (comment)) + consider returning a cxx::unique_ptr<id_t>
13. check invalid id logic (see Iox #605 cleanup relocatable ptr #618 (comment) and Iox #605 cleanup relocatable ptr #618 (comment))
14. add const methods to RelativePointer (see Iox #605 cleanup relocatable ptr #618 (comment), Iox #605 cleanup relocatable ptr #618 (comment) and Iox #605 cleanup relocatable ptr #618 (comment)). This might not be needed, compare with e.g. std::shared_pointer https://en.cppreference.com/w/cpp/memory/shared_ptr/operator* It should work similar to STL smart pointers.
15. invalidate other move c'tor and move assignment operator of BaseRelocatablePointer (see Iox #605 cleanup relocatable ptr #618 (comment) and Iox #605 cleanup relocatable ptr #618 (comment))
16. use composition instead of inheritance (see Iox #605 cleanup relocatable ptr #618 (comment) and Refactor Relocatable Pointer and Relative Pointer #605 (comment)) - if done, consider renaming Base...Pointer to Untyped...Pointer
17. replace RelativePointer by RelocatablePointer where applicable, e.g. Semaphore and LoFFLi Moved to Restructure RelativePointer unit tests #1745
18. Move RelativePointer to public include

[mossmaurice]

Moved open tasks to #1745