MISC: Improve several things relating to PID lookups (#1594)

findRunningScriptByPid needlessly took a "server" argument. This caused
there to be a "getRunningScriptByPid" version that did *not*, and it was
looping through all servers in order to function, which is needlessly
inefficient.

By removing the parameter and the needless inefficient helper method,
the following changes:
- Many Netscript functions such as isRunning() and getScript() become faster.
- The terminal "tail" command now works by pid regardless of the current
  server. Note that "kill" already worked this way.

I also improved the docs around "tail", since the pid argument wasn't
in the help.

src/ui/React/LogBoxManager.tsx

@@ -212,7 +212,7 @@ function LogWindow({ hidden, script, onClose }: LogWindowProps): React.ReactElem
   function run(): void {
     const server = GetServer(script.server);
     if (server === null) return;
-    const s = findRunningScriptByPid(script.pid, server);
+    const s = findRunningScriptByPid(script.pid);
     if (s === null) {
       const baseScript = server.scripts.get(script.filename);
       if (!baseScript) {