[Bug #21313] Handle it in rescue and ensure blocks.

The following is crashing for me:

```shell
ruby --yjit --yjit-call-threshold=1 -e '1.tap { raise rescue p it }'

ruby: YJIT has panicked. More info to follow...
thread '<unnamed>' panicked at ./yjit/src/codegen.rs:2402:14:
...
```

It seems `it` sometimes points to the wrong value:

```shell
ruby -e '1.tap { raise rescue p it }'
false

ruby -e '1.tap { begin; raise; ensure; p it; end } rescue nil'
false
```

But only when `$!` is set:

```shell
ruby -e '1.tap { begin; nil; ensure; p it; end }'
1

ruby -e '1.tap { begin; nil; rescue; ensure; p it; end }'
1

ruby -e '1.tap { begin; raise; rescue; ensure; p it; end }'
1
```

Author: nicholasdower

prism_compile.c

@@ -9640,7 +9640,19 @@ pm_compile_node(rb_iseq_t *iseq, const pm_node_t *node, LINK_ANCHOR *const ret,
         // -> { it }
         //      ^^
         if (!popped) {
-            PUSH_GETLOCAL(ret, location, scope_node->local_table_for_iseq_size, 0);
+            pm_scope_node_t *current_scope_node = scope_node;
+            int level = 0;
+
+            while (current_scope_node) {
+                if (current_scope_node->parameters && PM_NODE_TYPE_P(current_scope_node->parameters, PM_IT_PARAMETERS_NODE)) {
+                    PUSH_GETLOCAL(ret, location, current_scope_node->local_table_for_iseq_size, level);
+                    return;
+                }
+
+                current_scope_node = current_scope_node->previous;
+                level++;
+            }
+            rb_bug("Local `it` does not exist");
         }
 
         return;

test/ruby/test_syntax.rb

@@ -1946,6 +1946,14 @@ def test_it
     end
     assert_valid_syntax('proc {def foo(_);end;it}')
     assert_syntax_error('p { [it **2] }', /unexpected \*\*/)
+    assert_equal(1, eval('1.then { raise rescue it }'))
+    assert_equal(2, eval('1.then { 2.then { raise rescue it } }'))
+    assert_equal(3, eval('3.then { begin; raise; rescue; it; end }'))
+    assert_equal(4, eval('4.tap { begin; raise ; rescue; raise rescue it; end; }'))
+    assert_equal(5, eval('a = 0; 5.then { begin; nil; ensure; a = it; end }; a'))
+    assert_equal(6, eval('a = 0; 6.then { begin; nil; rescue; ensure; a = it; end }; a'))
+    assert_equal(7, eval('a = 0; 7.then { begin; raise; ensure; a = it; end } rescue a'))
+    assert_equal(8, eval('a = 0; 8.then { begin; raise; rescue; ensure; a = it; end }; a'))
   end
 
   def test_value_expr_in_condition