Checklist

• I have read the appropriate section in the contributing
  guidelines
• I believe this issue is a problem with polybar itself and not a misconfiguration on my part.
• I have searched for other open and closed issues that
  may have already reported this problem.
• I have checked the known issues page for this problem.

Describe the bug

Polybar creates its IPC socket in /tmp. This presents two problems:

• This is vulnerable to a symlink attack
• Many files may be present, forcing polybar-msg to process a long list of files

Expected behavior:
Polybar should create its socket in /run/user/XXXX/polybar/.

Actual behavior:
It creates it in /tmp.

I am willing to provide a patch if you agree with me.