Add defaults.update function.

[aabouzaid]

What does this PR do?

Add defaults.update function.

What issues does this PR fix or reference?

After enhancing defaults module with PR no. #44851 and #44850

I found that we have a lot of redundant in jinja, so this function is a combination of defaults.merge and defaults.deepcopy to avoid redundancy.

Here is an arbitrary example:

Yaml

group01:
  defaults:
    enabled: True
    extra:
      - test
      - stage
  nodes:
    host01:
      index: foo
      upstream: bar
    host02:
      index: foo2
      upstream: bar2

Expected output of group01.nodes.host01:

host01:
  index: foo
  upstream: bar
  enabled: True
  aggregate: source
  extra:
    - test
    - stage

Old style that done with Jinja:

{% for host, vars in group01.nodes.items() %}
  {% set defaults = salt['defaults.deepcopy'](group01.defaults) %}
  {% set host_vars = salt['defaults.merge'](defaults, vars) %}
  ....
{% endfor %}

The same thing with the new function defaults.update:

{% do salt['defaults.update'](group01.nodes, group01.defaults) %}

New Behavior

Better merge of defaults for groups.

Tests written?

Yes

Commits signed with GPG?

Yes

[aabouzaid]

@rallytime It's almost a year, when this function will be available please? 🤔

[rallytime]

It will be available in Fluorine.

[aabouzaid]

Ah, ok 👍
Thanks.