(core) Update sort and filter UI

Summary:
The sort and filter UI now has a more unified UI, with similar
capabilities that are accessible from different parts of Grist.
It's now also possible to pin individual filters to the filter bar,
which replaces the old toggle for showing all filters in the
filter bar.

Test Plan: Various tests (browser, migration, project).

Reviewers: jarek, dsagal

Reviewed By: jarek, dsagal

Subscribers: dsagal

Differential Revision: https://phab.getgrist.com/D3669

sandbox/grist/schema.py

@@ -15,7 +15,7 @@ import six
 
 import actions
 
-SCHEMA_VERSION = 33
+SCHEMA_VERSION = 34
 
 def make_column(col_id, col_type, formula='', isFormula=False):
   return {
@@ -315,7 +315,10 @@ def schema_create_actions():
       # `excluded` string to an array of column values:
       # Ex1: { included: ['foo', 'bar'] }
       # Ex2: { excluded: ['apple', 'orange'] }
-      make_column("filter",         "Text")
+      make_column("filter",         "Text"),
+      # Filters can be pinned to the filter bar, which causes a button to be displayed
+      # that opens the filter menu when clicked.
+      make_column("pinned",         "Bool"),
     ]),
 
     # Additional metadata for cells