MINOR: cfgparse/server: try to fix spelling mistakes on server lines

MINOR: cfgparse/server: try to fix spelling mistakes on server lines

Let's apply the fuzzy match to server keywords so that we can avoid
dumping the huge list of supported keywords each time there is a spelling
mistake, and suggest proper spelling instead:

  $ printf "listen f\nserver s 0 sendpx-v2\n" | ./haproxy -c -f /dev/stdin
  [NOTICE] 070/095718 (24152) : haproxy version is 2.4-dev11-caa6e3-25
  [NOTICE] 070/095718 (24152) : path to executable is ./haproxy
  [ALERT] 070/095718 (24152) : parsing [/dev/stdin:2] : 'server s' unknown keyword 'sendpx-v2'; did you mean 'send-proxy-v2' maybe ?
  [ALERT] 070/095718 (24152) : Error(s) found in configuration file : /dev/stdin
  [ALERT] 070/095718 (24152) : Fatal errors found in configuration.