relay admin helper commands (#985)
```
goat relay admin host list | jq .Host -r
truffle.us-east.host.bsky.network
pds.robocracy.org
grisette.us-west.host.bsky.network
pds.haileyok.com
agaric.us-west.host.bsky.network
pioppino.us-west.host.bsky.network
[...]
```
```
goat relay admin account takedown --reverse bnewbold.net
go run ./cmd/goat/ relay host add pds.example.com
```
```
goat relay account list --json | head
{"did":"did:plc:bpurujb3biqxm3rj6dq362co","head":"bafyreibdp33fixrpjztokl3yjhsfitha7iakfqoddpodhzy3lxqm4e7bi4","rev":""}
{"did":"did:plc:byrvqzvjg2wecnaw5wj42tbn","head":"bafyreiadhjx3h7wmeiolzagxxpd2s3sikypcnnrmkwzrfe6t42qo3vm4ki","rev":""}
{"did":"did:plc:x7hvipgsf3olqj2scs6vnfsx","head":"bafyreidagggvucwh5tieuj5erw4xfkh2y7evpidryp3mof6vnqmx7r42mu","rev":""}
{"did":"did:plc:bgzuexwoewroc5vvrjf6xdl3","head":"bafyreietjjrkuh34uh5dselwwqibp2o4nnvmq3ewpkiogkkqoeod5dp6gy","rev":""}
{"did":"did:plc:cahlsbuspvfckfoom6llqiao","head":"bafyreiappbl54e7m6bwcw53l6pxbuqgkshgqb6xwv3v3l2ym2aqwokgczu","rev":""}
{"did":"did:plc:bdru4kuod27akpllbusuvemz","head":"bafyreibfo74zbzqpwj4jtvltuhm5zxdja4qtuw6ovw3rgonk7qaidhjcyy","rev":""}
{"did":"did:plc:xaei4rjmliqrfhor6ncujtwo","head":"bafyreidf53dcsabb26g7eed4t6btu57u6wsai6ghp7mm4xjm2gjz5tootq","rev":""}
{"did":"did:plc:drwgwtoidbvxmbq5ix3uynnd","head":"bafyreiczyauyvcpj5n3r3rjwia2zpparse4xxcjijo5tv4kdl4bto2fxam","rev":""}
{"did":"did:plc:wz4f36gw3dudr64hbf4f6f4p","head":"bafyreiachwx45gha6hp4pdhiwtamufwfi67lxpskhdvnfxyhknumnswhbm","rev":""}
{"did":"did:plc:ixncuy6ec3pmvl7ni2auzqse","head":"bafyreieay3eueytuozikcssqd5ik4jesjkpmiuks2caf42bknm437bgg5e","rev":""}
```