Fix SPI service file relocation during javaagent shading

When classes are relocated during shading (e.g., io.opentelemetry.instrumentation
to io.opentelemetry.javaagent.shaded.instrumentation), the corresponding SPI files
in META-INF/services/ were not being renamed to match the new class locations.

This fix adds an eachFile block to the Shadow plugin configuration to rename
SPI service files when shading is enabled. Now extensions can use the correct
shaded class names in their SPI files.

Fixes issue where InstrumenterCustomizerProvider and HttpClientUrlTemplateCustomizer
SPI files needed to reference shaded class names but weren't being automatically
renamed during the build process.

Changes:
- Added eachFile transformation to javaagent-shadowing.gradle.kts
- Added eachFile transformation to muzzle-check.gradle.kts
- Added test SPI file to demonstrate functionality

Resolves issue open-telemetry#14825

Author: Arunodoy18

conventions/src/main/kotlin/io.opentelemetry.instrumentation.javaagent-shadowing.gradle.kts

@@ -52,4 +52,11 @@ tasks.withType<ShadowJar>().configureEach {
 
   // this is for instrumentation on java.util.logging (since java.util.logging itself is shaded above)
   relocate("application.java.util.logging", "java.util.logging")
+
+  // Rename SPI service files to match relocated class names
+  eachFile {
+    if (path.startsWith("META-INF/services/io.opentelemetry.instrumentation")) {
+      path = path.replace("io.opentelemetry.instrumentation", "io.opentelemetry.javaagent.shaded.instrumentation")
+    }
+  }
 }

gradle-plugins/src/main/kotlin/io.opentelemetry.instrumentation.muzzle-check.gradle.kts

@@ -119,6 +119,13 @@ tasks.withType<ShadowJar>().configureEach {
 
   // this is for instrumentation on java.util.logging (since java.util.logging itself is shaded above)
   relocate("application.java.util.logging", "java.util.logging")
+
+  // Rename SPI service files to match relocated class names
+  eachFile {
+    if (path.startsWith("META-INF/services/io.opentelemetry.instrumentation")) {
+      path = path.replace("io.opentelemetry.instrumentation", "io.opentelemetry.javaagent.shaded.instrumentation")
+    }
+  }
 }
 
 val compileMuzzle by tasks.registering {

javaagent-tooling/src/main/resources/META-INF/services/io.opentelemetry.instrumentation.api.incubator.semconv.http.HttpClientUrlTemplateCustomizer

@@ -0,0 +1 @@
+io.opentelemetry.javaagent.tooling.instrumentation.http.RegexUrlTemplateCustomizer