[asic-details] Add lotnum (4-character lot number) to SwitchIdentifiers

[zeeshanlakhani]

This PR adds lotnum (4-character lot number) to SwitchIdentifiers and exposes ASIC details via swadm (and the dpd-client API). The full lot identifier combines fab, lot, and lotnum (e.g., FTCAK7 instead of just T).

We do keep the current fields separated however, but update the view for the combination.

Adds v1::SwitchIdentifiers for API versions 1-4 (without lotnum), with the latest version (v5+) including the new field.

Fixes #200: Want swadm command to print Tofino ASIC details
Fixes #202: Not reporting full lot numbers in oximeter statistics

[zeeshanlakhani]

@bnaecker Took on this from the issues.

[rcgoodfellow]

Can we also include

• device id
• rev_num

Or maybe just all the fuse data?

The two above are combined to determine the chip rev, e.g.

 fn identifiers() -> anyhow::Result<()> {
     let pci =
         tofino::pci::Pci::new("/dev/tofino/1", tofino::REGISTER_SIZE).unwrap();
     let fuse = tofino::fuse::Fuse::read(&pci).unwrap();
     let chip_id: tofino::fuse::ChipId = fuse.chip_id.into();
     println!(
         "device id: {}",
         match fuse.device_id {
             0x0100 => "A0".to_owned(),
             0x0110 => match fuse.rev_num {
                 0 => "B0".to_owned(),
                 2 => "B1".to_owned(),
                 _ => format!("{:016x}", fuse.device_id),
             },
             _ => format!("{:016x}", fuse.device_id),
         }
     );
     println!("device rev: {}", fuse.rev_num);
     println!("chip id: {:016x}", fuse.chip_id);
     println!("{}", chip_id);
     Ok(())
 }

[zeeshanlakhani]

@rcgoodfellow I added the fuse info. I'll work on getting that piped through to oximeter when I update the schema in omicron next.

[bnaecker]

I don't think we'll realistically be able to update the schema for switch stats right now. The update mechanism we built predates the online update system we have now. That means there's never a period when at least one switch isn't producing data, and so no window in which the old data and schema can be updated reliably to make way for the new.

What I would do here is put this more complete value into the existing lot field, for the time being. When we can get back to solving actual schema update here in the context of reconfigurator, then we can migrate the schema and data as needed.

[zeeshanlakhani]

@bnaecker done.