fix(java): Run jdtls with a Lombok agent and show build errors at launch (#9)

* fix(java): Run jdtls with a Lombok agent and show build errors at launch

jdtls compiles with ECJ, which only generates Lombok members when the
server JVM runs -javaagent:lombok.jar. Nothing put it there, so @Data /
@Setter classes lost their accessors and Run launched stale classes
with "Unresolved compilation problem" stubs and no explanation.

- Projects whose build files mention Lombok get the newest jar: the
  IDE-managed one (new "Lombok (jdtls agent)" tool, latest release from
  Maven Central), else ~/.m2 (incl. settings.xml localRepository) or the
  Gradle cache. Each agent gets its own jdtls workspace so everything is
  rebuilt with it.
- Settings › Languages & Frameworks › Java › JVM options
  (java.jdt.ls.vmargs); a Lombok agent there wins.
- Run (and Debug, as a notification) list the first compile errors when
  the build has errors, plus a hint when Lombok is missing or older than
  1.18.34.

Fixes #3

* fix(java): Base the Lombok hint on the agent jdtls actually runs

A Lombok agent in Settings › Java › JVM options wins over the managed
and cached jars, but the launch hint still looked only at those: with
no cached jar it said Lombok was missing, and with an old cached one it
blamed that version although jdtls ran the user's. The hint and the
startup warning now use the user's agent (version from its file name).

src/platform/javaLaunch.ts

@@ -81,6 +81,15 @@ export function resolveJavaCommand(config: RunConfig, info: JavaLaunchInfo, path
   return { ...config, command, args };
 }
 
+/** Console report of a launch's compile errors (`path:line:col: error: …`) and their likely causes; "" when none. */
+export function formatCompileErrors(info: JavaLaunchInfo): string {
+  const lines = info.errors.map((e) => `${e.path}:${e.line}:${e.column}: error: ${e.message}`);
+  const more = info.errorCount - info.errors.length;
+  if (more > 0) lines.push(`… and ${more} more error${more === 1 ? "" : "s"} (see the Problems tool window)`);
+  lines.push(...info.hints);
+  return lines.length ? `${lines.join("\n")}\n` : "";
+}
+
 /** Joins arguments into one string for adapters that take `args` / `vmArgs` as text (java-debug). */
 export function joinJavaArgs(args: readonly string[]): string {
   return args.map((a) => (a === "" ? '""' : /[\s"]/.test(a) ? `"${a.replace(/(["\\])/g, "\\$1")}"` : a)).join(" ");