msi: Passing NULL for szBuffer and NULL for pcchValueBuf into MsiGetProductInfo{A, W} shouldn't crash.

Add a test for this.

In JOIN_fetch_int and JOIN_fetch_stream, prev_rows should be multiplied 
by the rows encountered in the current table so that prev_rows contains 
all of counts of the rows encountered multiplied together, rather than 
just the count of the rows in the last table encountered.

Store it in the URL cache entry and allow it to be retrieved by 
RetrieveUrlCacheEntryFile and other functions.

wininet: The URL in CommitUrlCacheEntryInternal shouldn't be restricted to MAX_PATH chars in length.

Dynamically allocate it and consolidate cleanup at the end of the function.

wininet: Fix URLCache_LocalFileNameToPathA to return a full path, rather than just the container path.

This was caused by path_len including the nul-terminator and so the rest 
of the string was being added after the nul-terminator, which is 
incorrect. This is fixed by making path_len not include the nul-terminator.

Also fix a few other issues with the function, like not passing a 
correct length into the second call to WideCharToMultiByte, nRequired 
being calculated incorrectly and the string not always being nul-terminated.

Add a test for this function by testing the lpszLocalFileName field 
obtained from RetrieveUrlCacheEntryFileA.

wininet: Use LIST_FOR_EACH_ENTRY in URLCacheContainers_FindContainerW instead of LIST_FOR_EACH and LIST_ENTRY.

wininet: Fix proxy authentication by using the data in lpwhr->pProxyAuthInfo in HTTP_InsertAuthorization instead of lpwhr->pAuthInfo when inserting the Proxy-Authentication header.

Otherwise, the wave-in driver(s) may copy incorrect data to internal structures.