Add todo component that supports multiple To-do lists.

[allenporter]

Proposed change

This updates the existing shopping-list card with support for managing multiple To-do lists using the todo component. The component is compatible with shopping-list and can support other integrations providing a To-do List.

The shopping_list panel is renamed to todo. However, to avoid confusion for existing shopping cart users, the icon still looks like a shopping card, but it has a check next to it like a to-do check.

The shopping_list card now can show a drop down list of a To-do list to select, or it can be configured with a specific To-do list to just show that list.

An alternative could be to leave shopping list alone and create another To-do List card, rather than going with this hybrid approach that could be a little confusing. Open to discussing the right approach for backwards compatibility as well as maintenance.

Work items:

• Fix translations
• Implement switching between entities
• Move edit commands to To-do list websocket APIs
• verify on a second todo implementation (e.g. local todo, todoist)

Initial demo extending Shopping list card to support To-do lists:

Type of change

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

Example configuration

Additional information

• Link to architecture proposal: New entity component: `todo` architecture#962
• Link to core pull request: Add todo component core#100019
• Link to brands pull request: Add icon for todo component brands#4682
• Link to documentation pull request: Add a to-do integration documentation home-assistant.io#28925
• Link to developer documentation pull request: Add todo component developer documentation developers.home-assistant#1929

Checklist

• The code change is tested and works locally.
• There is no commented out code in this PR.
• 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

[allenporter]

I am closing since @bramkragten is going to take this with a bigger scope.