Directives may need to be quoted on build

[aluttik]

Inside of certain blocks such as map, "directives" may contain whitespace characters, so we need to account for that.

For example, the inside of this block:

map $a $b {
  'Client A' 'value';
}

would be converted to this json:

{
    "directive": "Client A",
    "args": ["value"]
}

but that json would be converted back to nginx as:

map $a $b {
  Client A value;
}