Remove sockaddr type structs and socklen_t from internal core APIs, update POSIX tests

src/core/ext/client_config/client_config_plugin.c

src/core/ext/client_config/connector.h

src/core/ext/client_config/default_initial_connect_string.c

src/core/ext/client_config/initial_connect_string.c

src/core/ext/client_config/initial_connect_string.h

src/core/ext/client_config/parse_address.c

src/core/ext/client_config/parse_address.h

src/core/ext/client_config/subchannel.c

src/core/ext/client_config/subchannel.h

src/core/ext/client_config/subchannel_index.c

src/core/ext/lb_policy/grpclb/grpclb.c

src/core/ext/lb_policy/pick_first/pick_first.c

src/core/ext/lb_policy/round_robin/round_robin.c

src/core/ext/resolver/dns/native/dns_resolver.c

src/core/ext/resolver/sockaddr/sockaddr_resolver.c

...ore/ext/transport/chttp2/client/insecure/channel_create.c

...xt/transport/chttp2/client/secure/secure_channel_create.c

...core/ext/transport/chttp2/server/insecure/server_chttp2.c

...ext/transport/chttp2/server/secure/server_secure_chttp2.c

src/core/lib/http/httpcli.c