some minor fixes

[otavepto]

• set missing result data in Steam_UGC::SetUserItemVote(), missing boolean vote type (up or down)
• properly extract inventory item quantity in Steam_Inventory::GetResultItems(), use quantity json property
• properly implement Steam_Remote_Storage::UpdateUserPublishedItemVote(), update mod details in memory + don't restrict result to current player ID
• fix implementation of Steam_Remote_Storage::GetUserPublishedItemVoteDetails(), don't restrict result to current player ID
• minor fix for Steam_User_Stats::FindLeaderboard(), don't use lowercase since later comparison is done case-insensitive, also we have to keep the letter case otherwise some games will hang
• fix implementation of Steam_UGC::GetItemState(), the mod may be installed but not subscribed
• missing shutdown in controller
• missing objects destruction in steam_client + fix destruction order
• some casting + debug messages + comments
• remove duplicate helper function common_helpers::ascii_to_lowercase()