Allow spfs runtimes to have a description added to them for easier management later on

[dcookspi]

Add a description field to a spfs Runtime and display it in spfs runtime list, or have options to display it there.

People can name a spfs runtime with --runtime-name and keep a runtime around with --keep-runtime to make a durable runtime. And that's great, but the names are relatively short identifiers. Being able to add a description to a runtime you want to keep around would be useful when picking up the work/runtime later.

Describe the solution you'd like A clear and concise description of what you want to happen.

670759f7-819d-4263-88eb-c00cb2b5e563    running=false   pid=unknown editable=false  durable=false
1d23c37d-c209-4265-9f3c-091c5af1b9e5    running=false   pid=unknown editable=false  durable=false rollback plugin testing for show x because plugin y's release broken plugin z
show-y-dcc-from-spk                     running=false   pid=unknown editable=false  durable=false testing my dcc with the latest plugin x
5c62fedc-fa77-4cf7-9402-9420f7c644a6    running=false   pid=unknown editable=false  durable=false
...

[rydrman]

Makes sense to me