Add custom request header support to DevSupportHttpClient (facebook#55582)

Summary:
Pull Request resolved: facebook#55582

Add addRequestHeader/removeRequestHeader methods to DevSupportHttpClient. These allow callers to register custom HTTP headers that will be included in all requests made through both the httpClient and websocketClient.

Implemented via a shared OkHttp Interceptor that reads from a ConcurrentHashMap, so headers can be safely added/removed from any thread.

Changelog: [Internal]

Reviewed By: cipolleschi

Differential Revision: D93481539

fbshipit-source-id: e8d6bc4c9d21c65a0f4d95065eaadff776933c55

Author: cortinico

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/devsupport/inspector/DevSupportHttpClient.kt

@@ -9,17 +9,30 @@
 
 package com.facebook.react.devsupport.inspector
 
+import java.util.concurrent.ConcurrentHashMap
 import java.util.concurrent.TimeUnit
+import okhttp3.Interceptor
 import okhttp3.OkHttpClient
 
 /**
  * Shared [OkHttpClient] instances for devsupport networking. Uses a single connection pool and
  * dispatcher across all dev support HTTP and WebSocket usage.
  */
 internal object DevSupportHttpClient {
+  private val customHeaders = ConcurrentHashMap<String, String>()
+
+  private val headerInterceptor = Interceptor { chain ->
+    val builder = chain.request().newBuilder()
+    for ((name, value) in customHeaders) {
+      builder.header(name, value)
+    }
+    chain.proceed(builder.build())
+  }
+
   /** Client for HTTP requests: connect=5s, write=disabled, read=disabled. */
   val httpClient: OkHttpClient =
       OkHttpClient.Builder()
+          .addInterceptor(headerInterceptor)
           .connectTimeout(5, TimeUnit.SECONDS)
           .writeTimeout(0, TimeUnit.MILLISECONDS)
           .readTimeout(0, TimeUnit.MINUTES)
@@ -32,4 +45,14 @@ internal object DevSupportHttpClient {
           .connectTimeout(10, TimeUnit.SECONDS)
           .writeTimeout(10, TimeUnit.SECONDS)
           .build()
+
+  /** Add a custom header to be included in all requests made through both clients. */
+  fun addRequestHeader(name: String, value: String) {
+    customHeaders[name] = value
+  }
+
+  /** Remove a previously added custom header. */
+  fun removeRequestHeader(name: String) {
+    customHeaders.remove(name)
+  }
 }