[Feat] postgresql_parameters_extra var

[evgeny-bushuev-incountry]

Problem

Right now, to change a single option in the postgresql_parameters variable, I have to copy the entire dictionary from the common/defaults role into my inventory.

Description

It would be great to have a variable like postgresql_parameters_extra that could be merged with the default postgresql_parameters during playbook execution.

Importance

nice to have

Proposed implementation

postgresql_parameters: "{{ postgresql_parameters | community.general.lists_mergeby(postgresql_parameters_extra, 'option') }}"

[vitabaks]

You can use the local_postgresql_parameters variable to override defaults.

[evgeny-bushuev-incountry]

Host-level PostgreSQL parameters are defined locally in patroni.yml and override the common ones stored in DCS. Not quite what I needed, I still want these parameters to be in DCS

[vitabaks]

Feel free to suggest a PR.