search_pill: Rename non-user type to 'generic_operator'.

This change is meant to remove confusion between a pill's `type` being
"search" and its `operator` being "search".

web/src/search_pill.ts

@@ -32,7 +32,7 @@ export type SearchUserPill = {
 
 type SearchPill =
     | {
-          type: "search";
+          type: "generic_operator";
           operator: string;
           operand: string;
           negated: boolean | undefined;
@@ -51,7 +51,7 @@ export function create_item_from_search_string(search_string: string): SearchPil
         return undefined;
     }
     return {
-        type: "search",
+        type: "generic_operator",
         operator: search_term.operator,
         operand: search_term.operand,
         negated: search_term.negated,

web/tests/search.test.cjs

@@ -407,7 +407,7 @@ run_test("set_search_bar_contents with duplicate pills", () => {
     const pills = search.search_pill_widget._get_pills_for_testing();
     assert.equal(pills.length, 1);
     assert.deepEqual(pills[0].item, {
-        type: "search",
+        type: "generic_operator",
         operator: "has",
         operand: "attachment",
         negated: false,