Operation transformation infrastructure

Ability for extensions to register operation transformers. (This will likely be part of the resource transformation task AS7-4457.) Hooks to access that transformation registry during operation execution. This is to include:

1) Host level operations that target the slave HC directly but are proxied by the master HC.
2) Server level operations that target the slave HC's servers directly but are proxied by the master HC.
3) The first phase of domain-wide 2 phase operations where the master HC transmits the op to the slave HCs.
4) The second phase of domain-wide 2 phase operations where the master HC transmits server-level ops to the slave HCs for forwarding to their servers.

Item 4) above may be simple, as all the master HC is doing is executing ops according to instructions provided by the slave HCs in step 3). Those instructions will be correct for that slave HC.