Previously you couldn't have a brokerd backend which defined
`.trades_dialogue()` but which could also indicate that the paper
clearing engine should be used. This adds that support by allowing the
endpoint task to return a simple `'paper'` string, in which case the ems
will boot a paperboi.
The obvious useful case for this is if you have a broker you want to use
but do not have actual broker credentials setup (yet) with that provider
in your `brokers.toml`; demonstrated here with the adjustment to
`kraken`'s startup to no longer raise a runtime error B)
This will (likely) act as a new backend query endpoint for other `piker`
(client) code to lookup `MktPair` info from each backend. To start it
also returns the backend-broker's local `Pair` (or wtv other type) as
well.
The main motivation for this is for our paper engine which can require
the mkt info when processing paper-trades ledgers which do not contain
appropriate info to compute position metrics.
Apparently it will likely fix our `trio`-cancel-scopes-corrupted crash
when we try to let our `._web_bs.NoBsWs` do reconnect logic around
the asyn-generator implemented data-feed streaming routines in `binance`
and `kraken`. See the project docs for deatz; obvs we add the lib as
a dep.
Also includes a retyping of `Client._pair: dict[str, Pair]` to look up
pair structs and map all alt-key-name-sets to each for easy precision
info lookup to set the `.sym` field for each transaction including for
on-chain transfers which kraken provides as an "asset decimals" field,
presumably pulled from the particular block-token's limitation info.
Add decimal quantize API to Symbol to simplify by-broker truncation
Add symbol info to `pps.toml`
Move _assert call to outside the _async_main context manager
Minor indentation and styling changes, also convert a few prints to log calls
Fix multi write / race condition on open_pps call
Switch open_pps to not write by default
Fix integer math kraken syminfo _tick_size initialization
Trying to send a message in the `NoBsWs.fixture()` exit when the ws is
not currently disconnected causes a double `._stack.close()` call which
will corrupt `trio`'s coro stack. Instead only do the unsub if we detect
the ws is still up.
Also drops the legacy `backfill_bars()` module endpoint.
Fixes#437