Combine 'watch' and 'update' group actions

[wfarner]

In the trend of declarative state and idempotent actions, watch and update are currently outliers. Successfully choosing which one to invoke requires knowledge of the state of the cluster. There should be little adverse impact to combining them, essentially treating every watch as an update (which could begin from a blank state) will make InfraKit easier to use by humans and automation.

I propose we call the new verb commit meaning the following commands:

$ infrakit group watch group.json
$ infrakit group update group.json

would combine into

$ infrakit group commit group.json

The implication being that commit is an idempotent operation that does not depend on the current state of the cluster.

Additionally, i propose we replace the command:

$ infrakit group update-describe group.json

with

$ infrakit group commit group.json --pretend

[wfarner]

We currently also have infrakit group stop-update. I propose we approximate this behavior with infrakit group unwatch, which has similar behavior. unwatch may even be a better practice for the stopped-update case, as it makes it more clear that the group has been put into an unclear state.

Additionally i propose we rename unwatch as it no longer has an inverse. I'm proposing ignore.

[chungers]

My only thing with ignore is that it has a negative connotation, like when I ignore something bad will happen. How about free or release?

[wfarner]

@chungers yeah, i'm not settled yet on ignore. Personally, i'm less concerned with a negative connotation than i am with words that inaccurately imply behavior. free is okay, but seems awkward and incomplete without a symmetrical counterpart like malloc. release doesn't have this problem, but for some reason isn't clicking with me yet.

In case they trigger any thoughts, here's some other verbs that crossed my mind:
detach
drop
disconnect

[chungers]

I suppose release could mean 'releasing` from management/monitoring/babysitting... similar to unwatch.

detach and disconnect also have symmetric counterpart that aren't in this mix. drop feels like something left behind -- on par with ignore.

[wfarner]

Of the options so far i like release the most. Doesn't have the same 'delete' connotation as drop.

[wfarner]

@chungers i'm realizing now that release poses confusion with the concept of 'releasing software', as in 'deploying'. We should reconsider before landing the attached PR.

[chungers]

Good point. Maybe just 'umanaged' or 'unsupervised'? Not a verb though.

or 'SetSupervised' / 'SetUnsupervised'.

[wfarner]

To make progress, i'm going to proceed with free in the PR. We can revisit if this feels weird later on.