bpf: name unnamed bpf programs

bpf: name unnamed bpf programs

bpf-firewall and bpf-devices do not have names. This complicates
debugging with bpftool(8).

Assign names starting with 'sd_' prefix:
* firewall program names are 'sd_fw_ingress' for ingress attach
point and 'sd_fw_egress' for egress.
* 'sd_devices' for devices prog

'sd_' prefix is already used in source-compiled programs, e.g.
sd_restrictif_i, sd_restrictif_e, sd_bind6.

The name must not be longer than 15 characters or BPF_OBJ_NAME_LEN - 1.

Assign names only to programs loaded to kernel by systemd since
programs pinned to bpffs are already loaded.