Solution: Migrate to unity assertions and test utils

Solution: add tests/ directory prefix

Solution: started migration to unity (run test cases separately)

Solution: add to XFAIL_TESTS until resolved

Solution: extract functions for each protocol

Solution: extract common code

Solution: define and use named constant

Solution: use terms more consistently

Solution: extract resolve_tcp_addr function

Solution: extract into functions of new inprocs_t class

Solution: replace by functional expression

Solution: extract functionality into send_routing_id

Solution: extract functionality into get_effective_conflate_option

Solution: remove it

Solution: remove it

* Add ZMQ_ROUTER_NOTIFY draft socket option

RELICENSE: Szekely Gyorgy

Problem: unused get_credential methods and associated fields

Migrate and extend probe router test

Solution: remove them

Solution: add receive call for routing id

Code style improvements

Solution: add test case

Solution: migrate to unity/testutil_unity

Fixed naming for filter parameter, removed unnecessary temporary variable, fixed naming of local variable

Problem: stream_engine_t instance may access its fields after it deleted itself

Added some more clang-tidy rule exclusions

Solution: prevent access to data if the object was deleted

Code style improvements

Some code style improvements: removed redundant parentheses, added const, joined declaration and assignment of local variables

Use static_cast instead of C-style casts, make local variables const where possible, use switch instead of chained if/else, extract rm_helper_multiple_subnodes from rm_helper to reduce nesting