accessibility model - output codes

[smnorris]

https://github.com/smnorris/bcfishpass/blob/main/02_model/sql/model.sql burns output values to the streams table in the accessiblility_model_<species> columns.

CURRENT CODES

ACCESSIBLE - downstream of definite barriers and any modelled or assessed anthropogenic barriers
POTENTIALLY ACCESSIBLE - downstream of definite barriers, upstream of modelled anthropogenic barrier(s)
POTENTIALLY ACCESSIBLE - PSCIS BARRIER DOWNSTREAM - downstream of definite barriers, upstream of assessed PSCIS barrier / potential barrier

PROPOSED ADDITIONS

POTEENTIALLY ACCESSIBLE - PSCIS POTENTIAL DOWNSTREAM - upstream of crossing assessed as POTENTIAL
ACCESSIBLE - REMEDIATED - upstream of a remediated crossing, downstream of any other barriers

Remediated class would require extracting remediations into a separate temp table and running bcfishpass.py add-downstram-ids ...

[smnorris]

Closing for now, ACCESSIBLE - REMEDIATED is added.
Adding POTENTIALLY ACCESSIBLE - PSCIS POTENTIAL DOWNSTREAM is low priority at the moment.