Feature: on_schema_change for incremental models (#3387)

* detect and act on schema changes

* update incremental helpers code

* update changelog

* fix error in diff_columns from testing

* abstract code a bit further

* address matching names vs. data types

* Update CHANGELOG.md

Co-authored-by: Jeremy Cohen <jeremy@fishtownanalytics.com>

* updates from Jeremy's feedback

* multi-column add / remove with full_refresh

* simple changes from JC's feedback

* updated for snowflake

* reorganize postgres code

* reorganize approach

* updated full refresh trigger logic

* fixed unintentional wipe behavior

* catch final else condition

* remove WHERE string replace

* touch ups

* port core to snowflake

* added bigquery code

* updated impacted unit tests

* updates from linting tests

* updates from linting again

* snowflake updates from further testing

* fix logging

* clean up incremental logic

* updated for bigquery

* update postgres with new strategy

* update nodeconfig

* starting integration tests

* integration test for ignore case

* add test for append_new_columns

* add integration test for sync

* remove extra tests

* add unique key and snowflake test

* move incremental integration test dir

* update integration tests

* update integration tests

* Suggestions for #3387 (#3558)

* PR feedback: rationalize macros + logging, fix + expand tests

* Rm alter_column_types, always true for sync_all_columns

* update logging and integration test on sync

* update integration tests

* test fix SF integration tests

Co-authored-by: Matt Winkler <matt.winkler@fishtownanalytics.com>

* rename integration test folder

* Update core/dbt/include/global_project/macros/materializations/incremental/incremental.sql

Accept Jeremy's suggested change

Co-authored-by: Jeremy Cohen <jeremy@fishtownanalytics.com>

* Update changelog [skip ci]

Co-authored-by: Jeremy Cohen <jeremy@fishtownanalytics.com>

automatic commit by git-black, original commits:
  2799a8c
  bd70106

core/dbt/adapters/base/impl.py

@@ -476,9 +476,7 @@ def rename_relation(self, from_relation: BaseRelation, to_relation: BaseRelation
     @abc.abstractmethod
     @available.parse_list
     def get_columns_in_relation(self, relation: BaseRelation) -> List[BaseColumn]:
-        self, relation: BaseRelation
-    ) -> List[BaseColumn]:
-        """Get a list of the columns in the given Relation. """
+        """Get a list of the columns in the given Relation."""
         raise NotImplementedException(
             "`get_columns_in_relation` is not implemented for this adapter!"
         )