Correctly handle spaces/special characters in JAR path

Without this, we fail to correctly find our own JAR location,
which means we fail to self-test or attach.

Author: pimterry

src/main/kotlin/tech/httptoolkit/javaagent/AttachMain.kt

@@ -85,7 +85,7 @@ fun attachAgent(
 ) {
     val jarPath = File(
         ConstantProxySelector::class.java // Any arbitrary class defined inside this JAR
-            .protectionDomain.codeSource.location.path
+            .protectionDomain.codeSource.location.toURI()
     ).absolutePath
 
     // Inject the agent into the target VM