urldata: switch to uint* types more widely

urldata: switch to uint* types more widely

In particular, it turns 'unsigned long' into 'uint32_t' since the code
needs to build and run just as fine on Windows which has 32 bit longs,
so we know the code works with 32 bit field versions.

This makes Curl_easy 56 bytes smaller on my 64 bit Linux (maximized
build).

Closes #20209