Filter trust center subprocessors server-side

Subprocessor filtering for the compliance portal happens in the backend
rather than the client. Add a SubprocessorFilter (query, category,
country) to the trust API's subprocessors connection, thread it through
the resolver and service, and extend the coredata ThirdParty filter with
category equality and country array membership. The connection stores the
filter so totalCount reflects the filtered set. Add e2e coverage for the
new filtering.

On the frontend, convert the page to a refetchable fragment whose filter
arguments are driven by URL-persisted, debounced toolbar state (category
and region selects plus a search field), populate the dropdowns from an
unfiltered facet selection, and offer to clear filters from the empty
state.

Signed-off-by: Émile Ré <emile@probo.com>

pkg/coredata/third_party_filter.go

@@ -23,14 +23,24 @@ type (
 		showOnTrustCenter *bool
 		level             *int
 		query             *string
+		category          *ThirdPartyCategory
+		country           *CountryCode
 	}
 )
 
-func NewThirdPartyFilter(showOnTrustCenter *bool, level *int, query *string) *ThirdPartyFilter {
+func NewThirdPartyFilter(
+	showOnTrustCenter *bool,
+	level *int,
+	query *string,
+	category *ThirdPartyCategory,
+	country *CountryCode,
+) *ThirdPartyFilter {
 	return &ThirdPartyFilter{
 		showOnTrustCenter: showOnTrustCenter,
 		level:             level,
 		query:             query,
+		category:          category,
+		country:           country,
 	}
 }
 
@@ -39,6 +49,8 @@ func (f *ThirdPartyFilter) SQLArguments() pgx.StrictNamedArgs {
 		"show_on_trust_center": nil,
 		"filter_query":         nil,
 		"level":                nil,
+		"filter_category":      nil,
+		"filter_country":       nil,
 	}
 
 	if f.showOnTrustCenter != nil {
@@ -53,6 +65,14 @@ func (f *ThirdPartyFilter) SQLArguments() pgx.StrictNamedArgs {
 		args["level"] = *f.level
 	}
 
+	if f.category != nil {
+		args["filter_category"] = string(*f.category)
+	}
+
+	if f.country != nil {
+		args["filter_country"] = string(*f.country)
+	}
+
 	return args
 }
 
@@ -74,5 +94,15 @@ func (f *ThirdPartyFilter) SQLFragment() string {
 			name ILIKE '%' || @filter_query || '%'
 		ELSE TRUE
 	END
+	AND CASE
+		WHEN @filter_category::text IS NOT NULL THEN
+			category = @filter_category::third_party_category
+		ELSE TRUE
+	END
+	AND CASE
+		WHEN @filter_country::text IS NOT NULL THEN
+			@filter_country::country_code = ANY(countries)
+		ELSE TRUE
+	END
 )`
 }