fix(antminer): read power draw from the new_api stats payload - #325

…meter`

`send_rpc_command` wrapped every parameter value in cgminer's `parameter`
argument. Bitmain's `new_api` is not a `parameter` — it is a top-level flag
alongside `command`, and the firmware ignores it when nested, answering with
the legacy payload instead.

Every `new_api` helper on this client was affected: `stats`, `summary`,
`pools`, `rate`, `warning` and `reload` all requested the new API and silently
received the old one. The failure is invisible to a caller — the response is a
well-formed `STATUS: "S"` body, just the wrong shape.

Verified against L9 and L11 on 86.48-2.0.0:

    {"command":"stats","new_api":true}                -> STATS[1], "stats"
    {"command":"stats","parameter":{"new_api":true}}  -> STATS[2], "CGMiner stats"

The second is byte-identical to sending no parameter at all.

Object parameters now merge at the top level; scalars keep the `parameter`
wrapper, preserving cgminer's own convention for commands like `switchpool`
that take a pool index. Within this backend every parameter is currently a
`new_api` object, so nothing relied on the old wrapping.

Request construction is extracted into `build_rpc_request` so the wire format
is unit-testable without a socket.

…hape

Review feedback: check for the `new_api` key directly instead of inferring
top-level placement from the parameter being a JSON object.

`build_rpc_request` now removes `new_api` from the parameter object by name
and places it alongside `command`. Every other parameter — object or scalar —
keeps cgminer's `parameter` wrapper, so the generic object rule no longer
applies to payloads that never needed it.

The check stays inside `build_rpc_request` because `new_api` does not only
arrive through the typed helpers on this client: `APIClient::get_api_result`
forwards the parameters of a `MinerCommand::RPC` straight through, which is
the path a `GetDataLocations` entry takes. A dedicated `flags` argument on the
RPC command would be the place for further Bitmain extensions, but it means
changing `MinerCommand` in core, so it is left for when a second flag exists.

Tests renamed to describe the key rather than the shape, and two added: a
non-`new_api` object keeps the wrapper, and `new_api` is lifted out of a
larger object while the remaining keys stay wrapped.