gh-145398: Translate bracketed-paste start marker into an event

The event queue now turns the terminal's \x1b[200~ bracketed-paste
start sequence into a synthetic "bracketed paste" named event, so
readers can bind \<bracketed paste> instead of matching the raw
escape sequence directly.

Author: tanloong

Lib/_pyrepl/base_eventqueue.py

@@ -30,8 +30,13 @@
 from .console import Event
 from .trace import trace
 
+PASTE_KEYCODES = {
+    b'\033[200~': 'bracketed paste',
+}
+
 class BaseEventQueue:
     def __init__(self, encoding: str, keymap_dict: dict[bytes, str]) -> None:
+        keymap_dict.update(PASTE_KEYCODES)
         self.compiled_keymap = keymap.compile_keymap(keymap_dict)
         self.keymap = self.compiled_keymap
         trace("keymap {k!r}", k=self.keymap)

Lib/_pyrepl/keymap.py

@@ -98,6 +98,7 @@
     "space": " ",
     "tab": "\t",
     "up": "up",
+    "bracketed paste": "bracketed paste",
 }