Use ProcessHandle.of(pid) in ParentProcessWatcher

[fbricon]

Code from

lsp4mp/microprofile.ls/org.eclipse.lsp4mp.ls/src/main/java/org/eclipse/lsp4mp/ls/commons/ParentProcessWatcher.java

Lines 84 to 94 in c91e736

	// Wait until parent process id is available
	final long pid = server.getParentProcessId();
	if (pid == 0 || lastActivityTime > (System.currentTimeMillis() - INACTIVITY_DELAY_SECS)) {
	return true;
	}
	String command;
	if (isWindows) {
	command = "cmd /c \"tasklist /FI \"PID eq " + pid + "\" | findstr " + pid + "\"";
	} else {
	command = "kill -0 " + pid;
	}

could be updated to use ProcessHandle.of(pid), similar to eclipse-jdtls/eclipse.jdt.ls@c2f4710