Macro mentat_parser_utils::def_matches_plain_symbol

macro_rules! def_matches_plain_symbol {
    ( $parser: ident, $name: ident, $input: expr ) => { ... };
}

Generate a satisfy expression that matches a PlainSymbol value with the given name.

We do this rather than using combine::token so that we don't need to allocate a new String inside a PlainSymbol inside a SpannedValue inside a ValueAndSpan just to match input.