feat: Sanitize behavior

* Replace global `realworld` variable by a more explicit `backtest`
parameter  when registering middlewares
* Remove `bot` cli flag since this configuration was moved to insights
feat: Work offline, follow zipline development

* Fix consequences of `forex -> currencies:forex` in market.yml
* Replace `realworld` variable by a more explicit `backtest` parameter when registering middlewares
* Remove `bot` cli parameter since it was moved to *insights* plugins
* Expose `instant_fill` parameter in `properties`, default to `True`
* Fix trading environment setup, merge `build` and `__call_`
* Offline mode
* Clean up benchmark loaders
* Fix tests