[ILM] Support hybrid tier states on cloud

[jloleysens]

Summary

ILM UI needs to updated in the following ways for 7.10:

• On-prem UI should allow users to choose node role, node attributes or "off" for data allocation
• On cloud UI should allow users to choose node attributes or "off" for data allocation unless node roles are detected, then users should be able to choose node role, node attributes or "off" (same as on-prem)
• On cloud, once node roles have been set, the UI should show a call-to-action telling a user they can go to their cloud deployment to provision a cold tier

As discussed with @jethr0null @cjcenizal @jasontedor @bleskes this work needs to be done for the 7.10 release.

[elasticmachine]

Pinging @elastic/es-ui (Team:Elasticsearch UI)

[jloleysens]

Re-opening for now as there might some further tweaks required.

[jloleysens]

Reopening this one more time as there is one further change required:

We need to check for the presence of a data_* role before concluding that the cloud cluster is using new data roles AND the absence of the node.data: true setting.