test: add unit tests for header validation fixes

Add standalone test-runner with 7 tests covering both interceptor fixes:

CompressedResponseSizeInterceptor (AZ02):
- brokenInterceptor_failsWithArabicLocale: proves locale-dependent formatting crashes
- fixedInterceptor_succeedsWithArabicLocale: proves Locale.US fix works
- fixedInterceptor_succeedsWithUSLocale: regression test

BearerTokenInterceptor (AYPW):
- brokenInterceptor_failsWithControlCharInToken: proves corrupt tokens crash
- fixedInterceptor_succeedsWithControlCharInToken: proves sanitization works
- fixedInterceptor_skipsHeaderWhenTokenIsAllControlChars: edge case
- fixedInterceptor_passesCleanTokenUnmodified: regression test

Run with: cd test-runner && ./gradlew test

Co-authored-by: Claude <claude@anthropic.com>

Author: pavelzeman

test-runner/build.gradle.kts

@@ -0,0 +1,21 @@
+plugins {
+    kotlin("jvm") version "1.9.22"
+}
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    implementation("com.squareup.okhttp3:okhttp:4.12.0")
+    testImplementation("junit:junit:4.13.2")
+    testImplementation("com.squareup.okhttp3:mockwebserver:4.12.0")
+}
+
+sourceSets {
+    test {
+        kotlin {
+            srcDir("src/test/kotlin")
+        }
+    }
+}

test-runner/gradle/wrapper/gradle-wrapper.jar

@@ -0,0 +1,7 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.5-bin.zip
+networkTimeout=10000
+validateDistributionUrl=true
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists

test-runner/gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1 @@
+rootProject.name = "interceptor-tests"