Fix handling of absolute paths

This commit fixes the handling of absolute paths, switching from
`path.join()` to `path.isAbsolute()` to handle differing behavior for
different platforms.

`path.join()` works differently for Windows paths and Linux paths.
`path.join(".", "C:\\") === "C:\\"`
`path.join(".", "/home/test") === "home/test"`

The latter is missing a leading `/` and thus is no longer an
absolute path.

As described in [this issue](GHSA-37v4-cwgp-x353),
there was a NodeJS [security vulnerability](https://nodejs.org/en/blog/vulnerability/january-2025-security-releases)
that caused the behavior of `path.join()` to be changed. Newer versions
of Node will return a relative path in these instances, so
`path.join(".", "C:\\") === ".\\C:\\"`.

Author: BrendanC23

lib/java-caller.js

@@ -207,7 +207,8 @@ class JavaCaller {
         let allArgs = [];
         allArgs.push(...javaArgs);
         if (this.jar) {
-            const jarPath = path.join(this.rootPath, this.jar);
+            const jarPath = path.isAbsolute(this.jar) ? this.jar : path.join(this.rootPath, this.jar);
+            
             allArgs.push(
                 ...[
                     "-jar",

test/java-caller.test.js

@@ -177,8 +177,10 @@ describe("Call with classes", () => {
     });
 
     it("Should work with an absolute path", async () => {
+        const absolutePath = path.join(process.cwd(), "test/java/jar/JavaCallerTesterRunnable.jar");
+
         const java = new JavaCaller({
-            jar: path.join(process.cwd(), "test/java/jar/JavaCallerTesterRunnable.jar"),
+            jar: absolutePath,
         });
         const { status, stdout, stderr } = await java.run();