Incremental model show reason for on_schema_change fail failures (#5505)

* show reason for schema change failures

When the incremental model fails, I do not get the context I need to easily fix my discrepency.
Adding more info

* Update on_schema_change.sql

Fix identation

* Added changie changes

Added changie changes

* Update on_schema_change.sql

Trim whitespaces

* Update on_schema_change.sql

Log message text  enhancement

.changes/unreleased/Fixes-20220720-213746.yaml

@@ -0,0 +1,7 @@
+kind: Fixes
+body: on_shchma_change fail verbosity enhancement
+time: 2022-07-20T21:37:46.474241+03:00
+custom:
+  Author: Ilanbenb
+  Issue: "5504"
+  PR: "5505"

core/dbt/include/global_project/macros/materializations/models/incremental/on_schema_change.sql

@@ -119,6 +119,11 @@
                 - set the `on_schema_change` config to either append_new_columns or sync_all_columns, depending on your situation.
                 - Re-run the incremental model with `full_refresh: True` to update the target schema.
                 - update the schema manually and re-run the process.
+
+              Additional troubleshooting context:
+                 Source columns not in target: {{ schema_changes_dict['source_not_in_target'] }}
+                 Target columns not in source: {{ schema_changes_dict['target_not_in_source'] }}
+                 New column types: {{ schema_changes_dict['new_target_types'] }}
           {% endset %}
 
           {% do exceptions.raise_compiler_error(fail_msg) %}