[nexus] add alert_list and alert_view external API endpoints - #11072

control: job assigned to worker 01M00KQME0Y0R17HAMAQ0PTPYD [factory aws, i-08cfc1374aa8f367a] (queued for 54 s)
...
task: starting task 0: "setup"
task: process exited: duration 4183 ms, exit code 0
...
task: starting task 1: "rust-toolchain"
task: process exited: duration 17208 ms, exit code 0
...
task: starting task 2: "authentication"
task: process exited: duration 20 ms, exit code 0
...
task: starting task 3: "clone repository"
task: process exited: duration 11652 ms, exit code 0
...
task: starting task 4: "build"
...
| a out/probe.tar.gz 3037K
| a out/propolis-server.tar.gz 34642K
| a out/pumpkind-gz.tar 26647K
| a out/switch-softnpu.tar.gz 497219K
| 
| real     1:29.722330737
| user     1:26.684056909
| sys         5.137469783
| trap        0.006679315
| tflt        0.000000000
| dflt        0.000000000
| kflt        0.000000000
| lock        0.000000000
| slp      1:26.453143624
| lat         1.158489583
| stop        0.000193990
task: process exited: duration 1340373 ms, exit code 0
|W| found 1 output files
|W| uploading: /work/package.tar.gz (2759698574 bytes)
|W| uploaded: /work/package.tar.gz