feat(tests): [Bigtable] add conformance tests and proxy

Bigtable/tests/Conformance/proxy/.rr.yaml

@@ -0,0 +1,25 @@
+version: "3"
+rpc:
+  listen: "tcp://127.0.0.1:6001"
+
+server:
+  command: "php worker.php"
+  relay: "pipes"
+  relay_timeout: "20s"
+
+grpc:
+  listen: "tcp://127.0.0.1:9001"
+  proto: ["test_proxy.proto"]
+  max_send_msg_size: 50
+  max_recv_msg_size: 50
+  max_connection_idle: 0s
+  max_connection_age: 0s
+  max_connection_age_grace: 0s
+  max_concurrent_streams: 10
+  ping_time: 1s
+  timeout: 200s
+  pool:
+    num_workers: 2
+    max_jobs: 0
+    allocate_timeout: 60s
+    destroy_timeout: 60s

Bigtable/tests/Conformance/proxy/composer.json

@@ -0,0 +1,23 @@
+{
+    "name": "google-testing/proxy-bigtable-server",
+    "description": "Proxy Bigtable Server",
+    "repositories": [
+        {
+            "type": "path",
+            "url": "../../.."
+        }
+    ],
+    "require": {
+        "google/cloud-bigtable": "*",
+        "grpc/grpc": "^1.36",
+        "spiral/roadrunner-cli": "^2.6",
+        "spiral/roadrunner-grpc": "^3.4"
+    },
+    "autoload": {
+        "psr-4": {
+            "": "src"
+        }
+    },
+    "minimum-stability": "dev",
+    "prefer-stable": true
+}

Bigtable/tests/Conformance/proxy/ping.php

@@ -0,0 +1,17 @@
+<?php
+
+declare(strict_types=1);
+
+require __DIR__ . '/vendor/autoload.php';
+
+use Google\Bigtable\Testproxy\CreateClientRequest;
+
+$client = new \ProxyClient('127.0.0.1:9001', [
+    'credentials' => \Grpc\ChannelCredentials::createInsecure(),
+]);
+
+$message = new CreateClientRequest();
+
+[$response, $status] = $client->CreateClient($message)->wait();
+
+echo $response->serializeToJsonString() . PHP_EOL;