## Issue Addressed
NA
## Proposed Changes
Shift practically all HTTP endpoint handlers to the blocking executor (some very light tasks are left on the core executor).
## Additional Info
This PR covers the `rest_api` which will soon be refactored to suit the standard API. As such, I've cut a few corners and left some existing issues open in this patch. What I have done here should leave the API in state that is not necessary *exactly* the same, but good enough for us to run validators with. Specifically, the number of blocking workers that can be spawned is unbounded and I have not implemented a queue; this will need to be fixed when we implement the standard API.
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