Create DictMerge

[droans]

Adds ct_dict_merge as new function. Readme is updated with the function, description, and example.

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It's annoyed me for too long that the only real way to merge dictionaries in HA templates is:

{% set dict_a = {'a': 1, 'b': 2} %}
{% set dict_b = {'c': 3, 'd': 4} %}

{# Current method #}
{% set dict_a_ls = dict_a.items() | list %}
{% set dict_b_ls = dict_b.items() | list %}
{% set dict_c = dict.from_items(dict_a_ls + dict_b_ls) %}

{# Or #}
{% set dict_c = dict.from_items(dict_a.items() | list + dict_b.items() | list) %}

{# New Method #}
{% set dict_c = dict_merge(dict_a, dict_b) %}

I'm just using a single one-liner list comprehension for this. There is no limit on the number of dictionaries that can be passed to the function.

Preferably, we should just be able to add two dicts together or use either dict.update or {% set dict.key = val %} but those moves are disallowed in the HA Jinja templates.

[ildar170975]

Interesting, could you share a possible real application for this function?
Please post your answer in Community (https://community.home-assistant.io/t/custom-templates/528378) to avoid cluttering your PR with this info.

Update: I see it is posted, thanks a lot!

[PiotrMachowski]

Neat idea 👍

[PiotrMachowski]

Thank you, @droans!