[REF] mis_builder_cash_flow: Allow to override query

[SirAionTech]

In another module, we have added a column to mis.cash_flow.forecast_line and would like to use it in the MIS reports.

The problem is that the MIS reports do not use directly mis.cash_flow.forecast_line: they use the view mis.cash_flow that exposes only some selected fields of mis.cash_flow.forecast_line.

With this change, it is possible for other modules to change the view generation before it is executed.
This allows us to add the new column of mis.cash_flow.forecast_line in the view mis.cash_flow.

Any suggestion is appreciated: I admit I don't know MIS builder modules that well, so there may be other solutions for this use-case.
Please let me know what you think.

[OCA-git-bot]

Hi @jjscarafia,
some modules you are maintaining are being modified, check this out!

[rvalyi]

cc @marcelsavegnago