Adding additional xrefs to imports

Summary:
The pyrefly indexer does not always link the cross references with the corresponding import. This is causing issues for dead code bots. See https://www.internalfb.com/diff/D91318413?transaction_fbid=4540263059554165 and https://fb.workplace.com/groups/factsaboutcode/permalink/2782833315399232/

I started adding xrefs in D91681470, but we are still missing xrefs when we have transitive imports and when pyrefly returns the import as definition.

Reviewed By: donsbot

Differential Revision: D92156801

fbshipit-source-id: 3107ccf271bb6fb56642c891ce240f3ad53fa93e

Author: rubmary

glean/lang/python-pyrefly/tests/regression/without_dynamic_import/core/xrefs/declaration_reference.out

@@ -417,6 +417,19 @@
       "target": { "func": { "key": { "name": { "key": "lib.helper_func" } } } }
     }
   },
+  {
+    "key": {
+      "source": { "func": { "key": { "name": { "key": "main.f" } } } },
+      "target": {
+        "imp": {
+          "key": {
+            "as_name": { "key": "lib.func" },
+            "from_name": { "key": "big_lib.big_func" }
+          }
+        }
+      }
+    }
+  },
   {
     "key": {
       "source": { "func": { "key": { "name": { "key": "main.f" } } } },
@@ -1189,6 +1202,19 @@
       "target": { "func": { "key": { "name": { "key": "main.f" } } } }
     }
   },
+  {
+    "key": {
+      "source": { "module": { "key": { "name": { "key": "main" } } } },
+      "target": {
+        "imp": {
+          "key": {
+            "as_name": { "key": "lib.func" },
+            "from_name": { "key": "big_lib.big_func" }
+          }
+        }
+      }
+    }
+  },
   {
     "key": {
       "source": { "module": { "key": { "name": { "key": "main" } } } },

glean/lang/python-pyrefly/tests/regression/without_dynamic_import/core/xrefs/xrefs_via_name_by_file.out

@@ -550,6 +550,10 @@
           "source": { "length": 4, "start": 377 },
           "target": { "key": "big_lib.big_func" }
         },
+        {
+          "source": { "length": 4, "start": 377 },
+          "target": { "key": "lib.func" }
+        },
         {
           "source": { "length": 4, "start": 377 },
           "target": { "key": "main.func" }

glean/lang/python-pyrefly/tests/regression/without_dynamic_import/declaration_uses/simple/declaration_uses.out

@@ -188,6 +188,22 @@
       "span": { "length": 3, "start": 327 }
     }
   },
+  {
+    "key": {
+      "declaration": {
+        "imp": {
+          "key": {
+            "as_name": { "key": "mod_b.helper.only_indirectly" },
+            "from_name": { "key": "mod_b.util.only_indirectly" }
+          }
+        }
+      },
+      "file": {
+        "key": "glean/lang/python-pyrefly/tests/regression/without_dynamic_import/declaration_uses/simple/mod_a/__init__.py"
+      },
+      "span": { "length": 15, "start": 363 }
+    }
+  },
   {
     "key": {
       "declaration": { "module": { "key": { "name": { "key": "mod_b" } } } },

glean/lang/python-pyrefly/tests/regression/without_dynamic_import/declaration_uses/simple/xrefs_via_name_by_file.out

@@ -78,6 +78,10 @@
           "source": { "length": 15, "start": 363 },
           "target": { "key": "mod_a.only_indirectly" }
         },
+        {
+          "source": { "length": 15, "start": 363 },
+          "target": { "key": "mod_b.helper.only_indirectly" }
+        },
         {
           "source": { "length": 15, "start": 363 },
           "target": { "key": "mod_b.util.only_indirectly" }