cli: Allow usage without a `novem.conf`

[myme]

For CI workflows or other minimal systems it's not feasible to use the novem --init interactive workflow to create an initial novem.conf. The file can obviously be created manually, but that's quite user hostile.

The following should work, but doesn't: when there's no ~/.config/novem/novem.conf:

NOVEM_TOKEN=nut-this-is-not-a-token novem -p

and

novem --token nut-this-is-not-a-token -p

Example

Setting --config-path /dev/null (or just moving ~/.config/novem/novem.conf out of the way) doesn't let me list plots:

The issue is in building the config. It's possible to use /v1/whoami to fill the missing username, but requires one additional server round-trip.

[sondove]

I think it's perfectly reasonable that if there:

• is no config,
• but there is a token
• and there is a need for a username,

to do a roundtrip to whoami and fetch it.

[myme]

to do a roundtrip to whoami and fetch it.

I think this roundtrip is also already used for resolving job and repo refs:

novem-python/novem/job/__init__.py

Line 246 in 839f078

user = self.read("whoami")