Add possibility to ignore query

[anayrat]

Hello,
We noticed 80% of our powa database wheight was due to SET xxx statements which are not normalized.

It could be interesting to ignore a pattern as it is done in :
https://github.com/powa-team/powa-archivist/blob/master/powa--4.0.1.sql#L2260

We could add an "options" parameter to all functions of jsonb type and a column to powa_servers. Thus we will be able to give options for specifics server.

It implies to change all functions prototypes, the collector and the UI.

[rjuju]

+1

However it may be time to add a way to define "global settings", so that you don't have to setup the exact same parameter for every single foreign server.