fix(docs and code): text_hmi

[maciejmajek]

Purpose

Readme included wrong command for running the default streamlit based hmi.

Proposed Changes

• fix: typo in compare statement
• feat: allow empty identity and constitution in base hmi node
• docs: update text hmi command

Issues

• Links to relevant issues

Testing

Manually tested using

streamlit run src/rai_hmi/rai_hmi/text_hmi.py

and

ros2 run rai_whoami rai_whoami_node --ros-args -p robot_description_package:="rosbot_xl_whoami" & 
streamlit run src/rai_hmi/rai_hmi/text_hmi.py "rosbot_xl_whoami"