request help: key auth plugin didn't support get key from querystring

[forgaoqiang]

Issue description

I think it's a basic demand that the apikey should be check from HTTP header or HTTP Querystring, could you guys add that feature, It's very convenient to support both HTTP header and query string

Environment

Request help without environment information will be ignored or closed.

• apisix version (cmd: apisix version):
• OS (cmd: uname -a):
• OpenResty / Nginx version (cmd: nginx -V or openresty -V):
• etcd version, if have (cmd: run curl http://127.0.0.1:9090/v1/server_info to get the info from server-info API):
• apisix-dashboard version, if have:
• luarocks version, if the issue is about installation (cmd: luarocks --version):

[tokers]

@forgaoqiang PR's welcome to support it!

[forgaoqiang]

thanks for the feature