Fix z_view_string_t to std::string conversion

[fuzzypixelz]

Using AddressSanitizer, I found instances where a z_view_string_t was used to construct an std::string as if it was null-terminated, leading to rmw_zenoh reading garbage bytes.

[evshary]

LGTM. I think the CI failure is not caused by the changes.
Our dev/1.0.0 failed the CI again for an unknow issue

[YuanYuYuan]

Thanks @fuzzypixelz . Indeed, any plain z_string_data without length is wrongly used in the rmw_zenoh. I'll merge it and check the building error as I've already been working on this.

BTW, the solution to this is to construct a std::string to properly wrap it, but I think it could be improved. See ros2#325