Create default update wave strategy

[zmrow]

We need to create a default update wave strategy that's defined either in code or in some type of policy doc.

Ideally we could also define some accelerated and "ohgodohgod" strategies as well.

[sam-aws]

Throwing out some ideas:
Default - Very small wave over an hour, small group over the next few hours, 1-2 more waves over the subsequent day or two.
Accelerated - Similar to above but shrunk to a single day.
ohgodohgod - Small, quick initial wave and then immediate update for the rest of the fleet.

If we store this in the repo in some waves/default.json file, then we could have Updata and pipeline workers consume these directly.