MINOR: cfgparse: suggest correct spelling for unknown words in proxy sections

MINOR: cfgparse: suggest correct spelling for unknown words in proxy sections

Let's start by the largest keyword list, the listeners. Many keywords were
still not part of a list, so a common_kw_list array was added to list the
not enumerated ones. Now for example, typing "tmout" properly suggests
"timeout":

  $ printf "frontend f\ntmout client 10s\n" | ./haproxy -c -f /dev/stdin
  [NOTICE] 070/091355 (22545) : haproxy version is 2.4-dev11-3b728a-21
  [NOTICE] 070/091355 (22545) : path to executable is ./haproxy
  [ALERT] 070/091355 (22545) : parsing [/dev/stdin:2] : unknown keyword 'tmout' in 'frontend' section; did you mean 'timeout' maybe ?
  [ALERT] 070/091355 (22545) : Error(s) found in configuration file : /dev/stdin
  [ALERT] 070/091355 (22545) : Fatal errors found in configuration.