Parameterise auto_variables_triggers.

The `auto_variables_triggers` function is used to generate PostgreSQL triggers
to update some fields automatically. Currently it is triggered when any field
changes. For PB-1403 we want at least one of these triggers to be conditional
on specific fields.

This change replaces the raw-SQL-based `Condition('OLD.* IS DISTINCT FROM NEW.*')`
with `AnyChange(fields)`. This is equivalent as long as `fields` is empty. We
also update `auto_variables_triggers` to take a new optional `fields` argument
(defaulting to empty). This allows callers to define the conditions that apply
for the trigger.

A later change will make use of this new parametre.

Author: adk-swisstopo

app/stac_api/pgtriggers.py

@@ -3,7 +3,7 @@
 import pgtrigger
 
 
-def auto_variables_triggers(name):
+def auto_variables_triggers(name, *fields):
     '''Triggers used by various tables to update the `etag` and `updated` fields.'''
     auto_variables_func = '''
     -- update auto variables
@@ -25,7 +25,7 @@ def auto_variables_triggers(name):
             name=f"update_{name}_auto_variables_trigger",
             operation=pgtrigger.Update,
             when=pgtrigger.Before,
-            condition=pgtrigger.Condition('OLD.* IS DISTINCT FROM NEW.*'),
+            condition=pgtrigger.AnyChange(fields),
             func=auto_variables_func
         )
     ]