Added support for left-aligned radio cards

[joelstein]

The scenario

Users are accustomed to radio buttons with the indicator on the left. I'd like the ability to easily use this convention.

The problem

The indicator prop does not currently support left or start.

The solution

I extended the radio cards variant's indicator prop to accept a position. start/left render the indicator on the left side of the card, while end/right/true keep the existing right-aligned default, and false continues to hide it. The position can be set per card or on the group (inherited via @aware).

Fixes #2654.

[ghabriel25]

Hi @joelstein Have you try this with Blaze enabled?

[joelstein]

@ghabriel25 Yes, I tested it with Blaze enabled, and it works correctly.

[joshhanley]

@joelstein thanks for the PR! There was one small issue where $indicator was no longer being treated as truthy, like the original implemention had. So I've updated it to support that. Otherwise, all looks good to me.

[calebporzio]

Reviewed — indicator="start" (with left as an alias) matches how flux:switch handles its align prop, and since the indicator is placed by DOM order it flips correctly in RTL. Josh's truthiness fix covers the back-compat cases. Pushed a one-word spelling fix (behaviour → behavior) to match the codebase. Follow-up for us: mirror this on checkbox.cards so the two card variants stay in sync, and document the new accepted values.