tidy-up: miscellaneous

- H3 proxy: re-sync code with original source `curl_ngtcp2.c` to reduce
  differences, and to apply missed minor fixes. Also apply clang-format.
  Drop redundant `#undef`s, casts, `#endif` comments, includes, drop
  intermediate variables, sync include and macro order.
  Follow-up to e78b1b3ecc #21153
- INSTALL-CMAKE.md: move `CURL_ENABLE_SMB` to the enable section.
- tests/http/env: rename `tcpdmp` to `tcpdump` to match object variable.
- mbedtls: drop incorrect `mbedTLS 4+` comments.
  (features are also supported by 3+, meaning it's always supported.)
- lib1648: rename a variable to match purpose.
- CIPHERS.md: alpha-sort link list.
- replace rare `X''` hex markup with `0x`.
- `IP v4/6` -> `IPv4/6`.
- 'version X.Y' -> 'vX.Y', where sensible.
- 'VX.Y' -> 'vX.Y', where sensible.
- fix indents, casing, newlines, typos.

Closes #21772

tests/http/test_20_websockets.py

@@ -176,7 +176,7 @@ class TestWebsockets:
         r.check_exit_code(0)
 
     # Send large frames and simulate send blocking on 8192 bytes chunks
-    # Simlates error reported in #15865
+    # Simulates error reported in #15865
     @pytest.mark.parametrize("model", [
         pytest.param(1, id='multi_perform'),
         pytest.param(2, id='curl_ws_send+recv'),

tests/http/testenv/env.py

@@ -433,7 +433,7 @@ class EnvConfig:
         return self._h2o_version
 
     @property
-    def tcpdmp(self) -> Optional[str]:
+    def tcpdump(self) -> Optional[str]:
         return self._tcpdump
 
     def clear_locks(self):
@@ -677,7 +677,7 @@ class Env:
 
     @staticmethod
     def tcpdump() -> Optional[str]:
-        return Env.CONFIG.tcpdmp
+        return Env.CONFIG.tcpdump
 
     def __init__(self, pytestconfig=None, env_config=None):
         if env_config: