main: make matchnodes non-recursive

It's a little more sane this way.

src/_pytest/main.py

@@ -747,10 +747,13 @@ class Session(nodes.FSCollector):
         matching: Sequence[Union[nodes.Item, nodes.Collector]],
         names: Sequence[str],
     ) -> Sequence[Union[nodes.Item, nodes.Collector]]:
+        result = []
+        work = [(matching, names)]
+        while work:
             self.trace("matchnodes", matching, names)
             self.trace.root.indent += 1
 
-        result = []
+            matching, names = work.pop()
             for node in matching:
                 if not names:
                     result.append(node)
@@ -770,10 +773,10 @@ class Session(nodes.FSCollector):
                         if x.name == names[0] or x.name.split("[")[0] == names[0]:
                             submatching.append(x)
                     if submatching:
-                    result.extend(self.matchnodes(submatching, names[1:]))
+                        work.append((submatching, names[1:]))
                     # XXX Accept IDs that don't have "()" for class instances.
                     elif len(rep.result) == 1 and rep.result[0].name == "()":
-                    result.extend(self.matchnodes(rep.result, names))
+                        work.append((rep.result, names))
                 else:
                     # Report collection failures here to avoid failing to run some test
                     # specified in the command line because the module could not be
@@ -782,7 +785,6 @@ class Session(nodes.FSCollector):
 
             self.trace("matchnodes finished -> ", len(result), "nodes")
             self.trace.root.indent -= 1
-
         return result
 
     def genitems(