Implement header matching with type set to `header` under `match` directive

What

This MR is introducing a new header type matching under the match directive.

Why

As per #88, we're creating a new header matching logic, so we can be able to use following rule:

{
  "match": {
    "type": "header",
    "name": "force-cell",
    "regex_value": "^(?<cell_name>cell-\\d+)$"
  },
  "action": "classify",
  "classify": {
    "type": "SESSION_PREFIX",
    "value": "${cell_name}"
  }
}