add linuxquic implementation

Add linuxquic-interop docker image in implementations.json, and skip
it if the uapi header file /usr/include/linux/quic.h (kernel module)
doesn't exists in implementations.py.

Signed-off-by: Xin Long <lucien.xin@gmail.com>

Author: lxin

implementations.json

@@ -83,5 +83,10 @@
     "image": "us-central1-docker.pkg.dev/golang-interop-testing/quic/go-x-net:latest",
     "url": "https://pkg.go.dev/golang.org/x/net/internal/quic",
     "role": "both"
+  },
+  "linuxquic": {
+    "image": "quay.io/lxin/linuxquic-interop:latest",
+    "url": "https://github.com/lxin/quic",
+    "role": "both"
   }
 }

implementations.py

@@ -1,4 +1,5 @@
 import json
+import os
 from enum import Enum
 
 IMPLEMENTATIONS = {}
@@ -13,6 +14,8 @@ class Role(Enum):
 with open("implementations.json", "r") as f:
     data = json.load(f)
     for name, val in data.items():
+        if name == "linuxquic" and not os.path.exists("/usr/include/linux/quic.h"):
+            continue
         IMPLEMENTATIONS[name] = {"image": val["image"], "url": val["url"]}
         role = val["role"]
         if role == "server":