This commit adds the `data_hot`, `data_warm`, `data_cold`, and `data_frozen` node roles to the
x-pack plugin. These roles are intended to be the base for the formalization of data tiers in
Elasticsearch.
These roles all act as data nodes (meaning shards can be allocated to them). Nodes with the existing
`data` role acts as though they have all of the roles configured (it is a hot, warm, cold, and
frozen node).
This also includes a custom `AllocationDecider` that allows the user to configure the following
settings on a cluster level:
- `cluster.routing.allocation.require._tier`
- `cluster.routing.allocation.include._tier`
- `cluster.routing.allocation.exclude._tier`
And in index settings:
- `index.routing.allocation.require._tier`
- `index.routing.allocation.include._tier`
- `index.routing.allocation.exclude._tier`
Relates to #60848
e3df64a429