String

A string is single line, delimited by double quotes " only.

String       = double_quote, (escape_seq | string_char)*, double_quote

double_quote = '"'
escape_seq   = "\n"
             | '\"'
             | "\r"
             | "\\"
             | "\t"
string_char  = any_unicode_except_newline_and_double_quote

"hello"
""
"it's me"
"\"Mario\""thp
    

TODO: String interpolation