Clean-up introspection

## Brief feature description

Introspection needs a general clean-up.

## Detailed information

The introspection is in a messy state and needs to be cleaned-up. Also see #401 and #402.
To do:
- [ ] Use `typed_publisher`
- [ ] Remove reference to (removed) `field`s. Add history instead.
- [ ] Re-enable timing test `thread` in `test_roudi_port_introspection.cpp` (https://github.com/eclipse/iceoryx/pull/360#discussion_r535520323)
- [ ] Clean-up number of publisher port used for introspection (e.g. `PUBLISHERS_RESERVED_FOR_INTROSPECTION`). Question is if this number should be added to the specified number of ports or subtracted from them
- [ ] Comment in portmanager test `// clearing the introspection, is not in d'tor -> SEGFAULT in delete sporadically`