Jinja templating improvements

[depoll]

Breaking change

Proposed change

I've made some minor changes to the Jinja environment to add a few things that make it possible to improve performance and/or code reuse:

• break and continue for for loops
• Enabling importing/including shared jinja code/macros from a custom_jinja folder in your config folder
• as_mutable filter so that one can efficiently mutate a list or dictionary without rebuilding it from scratch in a loop
• do extension to make it possible to mutate lists/dicts.

All of this enables the following code:

In shared.jinja:

{% macro some_macro() -%}
A macro
{%- endmacro %}
{%- set some_constant = "A constant" %}

Elsewhere:

{% set mutableDict = {} | as_mutable %}
{% do mutableDict.update({'foo': 'bar'}) %}
{% set mutableList = [] | as_mutable %}
{% do mutableList.append("baz") %}

{{ mutableDict }}
{{ mutableList }}

{%- import "shared.jinja" as shared %}
{{ shared.some_constant }}
{{ shared.some_macro() }}

With the following output:

{'foo': 'bar'}
['baz']
A constant
A macro

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Deprecation (breaking change to happen in the future)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue:
• Link to documentation pull request:

I'm happy to update the documentation as well but wanted to first clear that this would be a welcome change.

Checklist

• The code change is tested and works locally.
• Local tests pass. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the development checklist
• The code has been formatted using Black (black --fast homeassistant tests)
• Tests have been added to verify that the new code works.

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated for www.home-assistant.io

If the code communicates with devices, web services, or third-party tools:

• The manifest file has all fields filled out correctly.
  Updated and included derived files by running: python3 -m script.hassfest.
• New or updated dependencies have been added to requirements_all.txt.
  Updated by running python3 -m script.gen_requirements_all.
• For the updated dependencies - a link to the changelog, or at minimum a diff between library versions is added to the PR description.
• Untested files have been added to .coveragerc.

To help with the load of incoming pull requests:

• I have reviewed two other open pull requests in this repository.

[depoll]

For context, I've added this based on use cases in my home. I'd love to be able to have some shared utilities/macros/constants to use across my automations. I also ended up with some performance problems due to a large number of incoming events from a slew of esphome devices across my home. I have a template sensor intercepting those events, but the recalculation is substantially slower than it needs to be because I'm constantly rebuilding lists and dictionaries (using a namespace, then making concatenating over and over again) instead of just updating a particular value (turning O(1) operations into O(n) and O(n^2) in many cases).

[emontnemery]

Thanks for the PR!

Please split this up to multiple PRs, where each PR adds a single new template feature.

[home-assistant]

Please take a look at the requested changes, and use the Ready for review button when you are done, thanks 👍

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[depoll]

Broke this out into 3 pull requests for each bit of functionality: #88624 #88625 #88626