progress: count amount of data "delivered" to application

... and apply the CURLOPT_MAXFILESIZE limit (if set) on that as well.
This effectively protects the user against "zip bombs".

Test case 1618 verifies using a 14 byte brotli payload that otherwise
explodes to 102400 zero bytes.

Closes #20787

src/tool_writeout.c

@@ -461,6 +461,8 @@ static const struct writeoutvar variables[] = {
   { "remote_port", VAR_PRIMARY_PORT, CURLINFO_PRIMARY_PORT, writeLong },
   { "response_code", VAR_HTTP_CODE, CURLINFO_RESPONSE_CODE, writeLong },
   { "scheme", VAR_SCHEME, CURLINFO_SCHEME, writeString },
+  { "size_delivered", VAR_SIZE_DELIVERED, CURLINFO_SIZE_DELIVERED,
+    writeOffset },
   { "size_download", VAR_SIZE_DOWNLOAD, CURLINFO_SIZE_DOWNLOAD_T,
     writeOffset },
   { "size_header", VAR_HEADER_SIZE, CURLINFO_HEADER_SIZE, writeLong },

src/tool_writeout.h

@@ -90,6 +90,7 @@ typedef enum {
   VAR_REFERER,
   VAR_REQUEST_SIZE,
   VAR_SCHEME,
+  VAR_SIZE_DELIVERED,
   VAR_SIZE_DOWNLOAD,
   VAR_SIZE_UPLOAD,
   VAR_SPEED_DOWNLOAD,