standalone: add simple instance attestation server - #1076

control: job assigned to worker 01KKB1D01VT6SRGWK9DCSHYB35 [factory gimlet-EVT22200007-propolis, EVT22200007/60864] (queued for 26 s)
...
task: starting task 0: "setup"
task: process exited: duration 3074 ms, exit code 0
...
task: starting task 1: "rust-toolchain"
task: process exited: duration 21748 ms, exit code 0
...
task: starting task 2: "authentication"
task: process exited: duration 64 ms, exit code 0
...
task: starting task 3: "clone repository"
task: process exited: duration 2245 ms, exit code 0
...
task: starting task 4: "build"
...
|   --- stderr
|   Error: executing command "pki-playground"
| 
|   Caused by:
|       No such file or directory (os error 2)
| warning: build failed, waiting for other jobs to finish...
| 
| real     3:08.161242855
| user    14:49.346629282
| sys      3:25.611890405
| trap        0.512219715
| tflt        0.401861031
| dflt        0.201448658
| kflt        0.002744891
| lock    29:56.399211857
| slp     59:46.689082051
| lat      1:33.693519299
| stop     5:14.509557534
task: process exited: duration 323787 ms, exit code 101
|W| found 0 output files