Parser: Improve ERB case node and end tag matching (#1237)

This pull request improves the parser by properly matching `<% end %>`
tags to `ERBCaseNode` when no `when`/`in` clauses are present.

For the following example:
```html+erb
<% case 1 %>
<% end %>
```
The reported errors are now reduced to 1, down from 3.

**Before**

```
Errors (3 total)

  1. RubyParseError at test.html.erb:1:3
     case_missing_conditions: expected a `when` or `in` clause after `case`

  2. MissingERBEndTagError at test.html.erb:1:0
     `<% case %>` started here but never closed with an end tag. The end tag may be in a different scope.

  3. ERBControlFlowScopeError at test.html.erb:2:0
     `<% end %>` appears outside its control flow block. Keep ERB control flow statements together within the same HTML scope (tag, attribute, or content).
```

**After**
```
Errors (1 total)

  1. RubyParseError at test.html.erb:1:3
     case_missing_conditions: expected a `when` or `in` clause after `case`
```


Inspired by ruby-gettext/gettext#117

/cc @joelhawksley

Author: marcoroth

src/analyze.c

@@ -656,7 +656,7 @@ static size_t process_control_structure(
         AST_ERB_CONTENT_NODE_T* erb_content = (AST_ERB_CONTENT_NODE_T*) next_node;
         control_type_t next_type = detect_control_type(erb_content);
 
-        if (next_type == CONTROL_TYPE_WHEN || next_type == CONTROL_TYPE_IN) { break; }
+        if (next_type == CONTROL_TYPE_WHEN || next_type == CONTROL_TYPE_IN || next_type == CONTROL_TYPE_END) { break; }
       }
 
       hb_array_append(non_when_non_in_children, next_node);

test/parser/case_when_test.rb

@@ -109,5 +109,21 @@ class CaseWhenTest < Minitest::Spec
         <% end %>
       HTML
     end
+
+    test "case without when" do
+      assert_parsed_snapshot(<<~HTML)
+        <% case 1 %>
+        <% end %>
+      HTML
+    end
+
+    test "case with single when" do
+      assert_parsed_snapshot(<<~HTML)
+        <% case 1 %>
+        <% when 1 %>
+          <p>one</p>
+        <% end %>
+      HTML
+    end
   end
 end