Appends something like name=value to string, taking care to quote value if
needed, and if so, to escape any quotes or backslashes in value.
Alternatively, if value is a non-ASCII UTF-8 string, it will be appended using RFC5987 syntax. Although in theory this is
supposed to work anywhere in HTTP that uses this style of parameter, in reality, it can only be used portably with the Content-Disposition
"filename" parameter.
If value is null, this will just append name to string.
| string |
a StringBuilder being used to construct an HTTP header value |
| name |
a parameter name |
| value |
a parameter value, or |