Add openexchangerates config flow (#76390)

.coveragerc

CODEOWNERS

homeassistant/components/openexchangerates/__init__.py

homeassistant/components/openexchangerates/config_flow.py

homeassistant/components/openexchangerates/const.py

homeassistant/components/openexchangerates/coordinator.py

homeassistant/components/openexchangerates/manifest.json

homeassistant/components/openexchangerates/sensor.py

homeassistant/components/openexchangerates/strings.json

...sistant/components/openexchangerates/translations/en.json

homeassistant/generated/config_flows.py

requirements_test_all.txt

tests/components/openexchangerates/__init__.py

tests/components/openexchangerates/conftest.py

tests/components/openexchangerates/test_config_flow.py