altcp_tls: rename altcp_tls_new -> altcp_tls_wrap, add altcp_tls_new

The new altcp_tls_new() is a type safe version of altcp_tls_alloc()

Signed-off-by: Simon Goldschmidt <goldsimon@gmx.de>

altcp_tls_alloc: need to close inner conn instead of freeing it

altcp: simplify creating different types by adding an allocator concept

This is done with an example in the http_client

Signed-off-by: goldsimon <goldsimon@gmx.de>