v3.0.x certs: Don't drop extensions when creating server certificates; doc and Makefile tidy (#3529)
* certs: Reorder the deps for the Makefile targets
Makes the output of running `make` more logical: First the all the CA
certs steps, then the server cert steps, then the client cert steps.
* certs: Include configured extensions in the server and inner-server certs
We set "[ CA_default ] ... copy_extensions = copy" to ensure that the
basic constrains, key usage and subject alternate name extensions set in
the config file and included in the CSR are actually applied to the