protocols: advertise tearing-control + fractional-scale

Add wp_tearing_control_manager_v1 and wp_fractional_scale_manager_v1 as
pass-through advertisements for client convenience (games, HiDPI).  kick
drives a vsynced scene at scale 1.0, so nothing is honoured: a new
tearing object is only logged at DEBUG.  Bundle the output-power XML
locally too (needed by a later commit) and generate the server headers
the wlroots headers' quoted includes require.

tests/test_smoke.py

@@ -3365,3 +3365,26 @@ def test_standalone_headless_screencopy_frame(tmp_path):
     finally:
         s.close()
 
+
+def test_standalone_headless_tearing_and_fractional_globals(tmp_path):
+    """The compositor advertises wp_tearing_control_manager_v1 (games request
+    unthrottled presentation) and wp_fractional_scale_manager_v1 (clients
+    learn a non-integer scale).  kick drives a vsynced scene at scale 1.0,
+    so both are pass-through: advertised but nothing honoured."""
+    out = tmp_path / "globals.txt"
+    s = _spawn_standalone({}, "%s --globals-out '%s' '#112233'" % (WL, out))
+    try:
+        deadline = time.monotonic() + 15.0
+        while time.monotonic() < deadline:
+            if out.exists():
+                break
+            time.sleep(0.1)
+        assert out.exists(), "wltest --globals-out never wrote its file"
+        names = {line.split()[0] for line in out.read_text().splitlines()}
+        for want in ("wp_tearing_control_manager_v1",
+                     "wp_fractional_scale_manager_v1"):
+            assert want in names, \
+                f"missing global {want}; advertised: {sorted(names)}"
+    finally:
+        s.close()
+