Add support to single quoted strings for {string}

[fcr--]

To be able to use strings quoted with single quotes for the {string} parameters, it would be good to add an option expanding {string} to '\'[^\']*\''.

Maybe adding a cucumberautocomplete.singleQuoteString option.

[alexkrechik]

Finally decided, that it would be better to use customParameters option here (due to there are so many extensions options and it's better to try to avoid more options adding):

"cucumberautocomplete.customParameters": [{
       "parameter": "{string}",
       "value": "'[^']*'"
   }]

[alexkrechik]

Please reopen issue/write here if suggested way doesn't work to you.