Add BF4 PCI-derived representor naming to dpu-agent

[bcavnvidia]

The dpu-agent currently assumes a simple naming convention for representors (e.g. pf0hpf(_if) for the representor of the primary DPU host representor).

That naming convention changes with BF4:

Type	Old (BF2/BF3)	New (BF4)
Uplink representors	p0, p1	p0, p1 (unchanged)
PF host representors	pfhpf	B{domain}{bus}c1pf
VF representors	pfvf	B{domain}{bus}c1pfvf
SF representors	en3f0pf0sf	B{domain}pfsf
SF netdevs	en3f0pf0sf	enP{domain}p{bus}s{dev}f{func}S{sfnum}

Scope

• Classify known BF4 DPU part numbers.
• Derive PF0/PF1 domain and bus from hardware discovery.
• Resolve representor names locally
• Preserve legacy naming for older and unknown hardware.
• Reject incomplete BF4 topology instead of using an incorrect fallback.

Future Work

Extend the init-container hardware cache with a doca_caps representor map,
then use it for SF and traffic-intercept naming.

[bcavnvidia]

Downgrading priority and removing from phase 1 because it so far looks like DPF abstracts it away enough that we don't have to worry until we need to touch interfaces directly on the ARM OS.