Report support for OSC52 write to clipboard in DA1

There are apparently some applications that want to only turn on OSC52
if they can be sure the terminal supports it.
https://github.com/contour-terminal/vt-extensions/blob/master/clipboard-extension.md

Seems harmless enough, though IMO the correct query mechanism for
runtime controllable settings is XTGETTCAP, but, let's be a
good citizen and co-operate. The overhead is not too large and I
have more important windmills to tilt at.

Fixes #8788

kitty_tests/__init__.py

@@ -24,7 +24,7 @@ from kitty.options.types import Options, defaults
 from kitty.rgb import to_color
 from kitty.types import MouseEvent
 from kitty.utils import read_screen_size
-from kitty.window import decode_cmdline, process_remote_print, process_title_from_child
+from kitty.window import da1, decode_cmdline, process_remote_print, process_title_from_child
 
 
 def parse_bytes(screen, data, dump_callback=None):
@@ -132,10 +132,14 @@ class Callbacks:
         self.last_cmd_cmdline = ''
         self.last_cmd_at = 0
         self.num_of_resize_events = 0
+        self.da1 = []
 
     def on_bell(self) -> None:
         self.bell_count += 1
 
+    def on_da1(self) -> None:
+        self.da1.append(da1(get_options()))
+
     def on_activity_since_last_focus(self) -> None:
         pass
 

kitty_tests/screen.py

@@ -407,6 +407,15 @@ class TestScreen(BaseTest):
         parse_bytes(s, b'\x1b[?2048h')  # ]
         self.ae(c.num_of_resize_events, 2)
 
+    def test_da1(self):
+        s = self.create_screen()
+        parse_bytes(s, b'\x1b[c\x1b[0c')  # ]]
+        self.ae(s.callbacks.da1, ['?62;52;c', '?62;52;c'])  # ]]
+        s.callbacks.clear()
+        self.create_screen(options={'clipboard_control': 'read-clipboard'})
+        parse_bytes(s, b'\x1b[c')  # ]]
+        self.ae(s.callbacks.da1, ['?62;c'])  # ]]
+
     def test_cursor_after_resize(self):
 
         def draw(text, end_line=True):