clean up PSCIS fix tables

[smnorris]

Existing issues:

• update PSCIS-modelled crossings-streams fix table when linked modelled crossing no longer exists (road removed from mapping) #674
• PSCIS 199306 not being linked to crossing 13900028 #660
• update fix table data to handle updates upstream in PSCIS  #621
• pscis_modelledcrossings_streams_xref - improve ability to precisely locate a crossing by including blkey/measure instead of linear_feature_id #620
• PSCIS barrier status fix table usage #521

My initial thoughts for simplifying/standardizing PSCIS fixes is to consider combining the two current PSCIS fix tables.

A single file could have fields for adjusting:

• modelled crossing matching
• location adjustment (via blue_line_key / measure instead of current linear_feature_id)
• barrier status
• structure type
• other?

[smnorris]

Additional fields:
wcrp_exclude boolean - exclude the PSCIS crossing from WCRP reporting (ie, crossings_wcrp_vw)
wcrp_exclude_notes text - why the crossing should be excluded.

These are for crossings where no structure exists. I'm not clear on how these differ from fords but this is a convenient way to remove them from WCRP reporting.