Support parsing chunk-extension for Transfer-Encoding: chunked

Request for example:
```
PUT <url> HTTP/1.1
Host: <ip:port>
Transfer-Encoding: chunked
10;ext1=value1;ext2=value2
...
```
Need callback for full extension ext1=value1;ext2=value2 or each extention value. May be implement it as for simple HTTP headers -- callback for header-name and callback for header-value