Add template list functions: intersect, difference, symmetric_difference, union

[frenck]

Proposed change

Add template functions and filters for list operations: intersect(), difference(), symmetric_difference(), union()

These functions provide set-like operations for lists in templates, making it easier to work with collections of values.

Signatures:

intersect(value: Iterable[Any], other: Iterable[Any]) -> list[Any]
difference(value: Iterable[Any], other: Iterable[Any]) -> list[Any]
symmetric_difference(value: Iterable[Any], other: Iterable[Any]) -> list[Any]
union(value: Iterable[Any], other: Iterable[Any]) -> list[Any]

Examples:

# Find common elements between lists
{{ intersect([1, 2, 5, 3, 4, 10], [1, 2, 3, 4, 5, 11, 99]) }} # renders as `[1, 2, 3, 4, 5]`
{{ [1, 2, 5, 3, 4, 10] | intersect([1, 2, 3, 4, 5, 11, 99]) }} # renders as `[1, 2, 3, 4, 5]`

# Find elements in the first list, not inthe  second list
{{ difference([1, 2, 5, 3, 4, 10], [1, 2, 3, 4, 5, 11, 99]) }} # renders as `[10]`
{{ [1, 2, 5, 3, 4, 10] | difference([1, 2, 3, 4, 5, 11, 99]) }} # renders as `[10]`

# Find elements that are in either list but not in both
{{ symmetric_difference([1, 2, 5, 3, 4, 10], [1, 2, 3, 4, 5, 11, 99]) }} # renders as `[10, 11, 99]`
{{ [1, 2, 5, 3, 4, 10] | symmetric_difference([1, 2, 3, 4, 5, 11, 99]) }} # renders as `[10, 11, 99]`

# Combine all unique elements from two lists
{{ union([1, 2, 5, 3, 4, 10], [1, 2, 3, 4, 5, 11, 99]) }} # renders as `[1, 2, 3, 4, 5, 10, 11, 99]`
{{ [1, 2, 5, 3, 4, 10] | union([1, 2, 3, 4, 5, 11, 99]) }} # renders as `[1, 2, 3, 4, 5, 10, 11, 99]`

Each function can be used either as a function or as a filter and works with any iterable input. The functions handle both numeric and string values, making them versatile for various use cases in templates.

Type of change

• [ ] Dependency upgrade
• [ ] Bugfix (non-breaking change which fixes an issue)
• [ ] New integration (thank you!)
• [x] 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: https://github.com/home-assistant/home-assistant.io/pull/38190
• Link to developer documentation pull request:
• Link to frontend pull request:

Checklist

• [x] The code change is tested and works locally.
• [x] Local tests pass. Your PR cannot be merged unless tests pass
• [x] There is no commented out code in this PR.
• [x] I have followed the development checklist
• [x] I have followed the perfect PR recommendations
• [x] The code has been formatted using Ruff (ruff format homeassistant tests)
• [x] 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.

To help with the load of incoming pull requests:

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