fix: :and ref query should return nodes that having at least one ref (#12085)

This commit also adds a new :self-ref rule.

`[[page]]` will uses :self-ref,
`(or [[page1]] [[page2]])` will be `(or [:self-ref page1] [:self-ref
page2]`.
`(and [[page1]] [[page2]])` will be `(and [:page-ref page1] [:page-ref
page2] (or [:self-ref page1] [:self-ref page2]))` to ensure the query
result nodes to have at least one page reference.

src/test/frontend/db/query_dsl_test.cljs

@@ -598,6 +598,7 @@ prop-d:: [[nada]]"}])
                      :file/content "foo:: bar
 - b1 [[page 1]] [[tag2]]
 - b2 [[page 2]] [[tag1]]
+  - b4 [[page 4]] [[tag4]]
 - b3"}])
 
   (testing "page-ref queries"
@@ -625,9 +626,16 @@ prop-d:: [[nada]]"}])
                 (dsl-query "(or [[tag2]] [[page 2]])")))
         "OR query")
 
+    (comment
+      ;; FIXME: load-test-files doesn't save `b4` to the db when DB_GRAPH=1
+      (is (= ["b1" "b4"]
+             (map testable-content
+                  (dsl-query "(or [[tag2]] [[page 4]])")))
+          "OR query"))
+
     (is (= ["b1"]
            (map testable-content
-                (dsl-query "(or [[tag2]] [[page 3]])")))
+                (dsl-query "(or [[tag2]] [[page not exists]])")))
         "OR query with nonexistent page should return meaningful results")
 
     (is (= (if js/process.env.DB_GRAPH #{"b1" "bar" "b3"} #{"b1" "foo:: bar" "b3"})