Asset page should not fail if entity address can't be constructed

[nhoening]

When running FlexMeasures on something else than localhost, visiting the asset page can lead to

Exception : "Could not find out when authority for started. Is FLEXMEASURES_HOSTS_AND_AUTH_START configured for it?

We are using entity address scheming as defined by USEF to give sensors domain-specific, stable identification (and as domains can change ownership over time, this requires us to know which ownership period was used to create the entity address).

When using localhost, we don't require this setting and assume ownership started this month (see utils/entity_address_utils.py::build_ea_scheme_and_naming_authority).

What fails here is to generate the entity addresses of the sensors, which are listed on the asset page.

I believe that the page should still render, but somehow fail more gently here.

In addition, we should check if the right warnings or errors about this are given when starting FlexMeasures.