action_sheet: Use directional border radius for reaction buttons

[yash-agarwa-l]

This fixes the border radius of the reaction buttons in the message action sheet for RTL languages.

Previously, the "First" button (e.g., thumbs up) and the "More" button (...) had hardcoded rounded corners. In RTL mode, these corners remained on the physical side, which resulted in the inner corners being rounded instead of the outer ones.

We now use BorderRadiusDirectional resolved against the text direction to ensure the outer edges are always the ones rounded.

This addresses the third RTL issue identified by @gnprice in this comment.

Before

Component	LTR (English)	RTL (Arabic)
First Button (Thumbs Up)
Last Button (More ...)

After

Component	LTR (English)	RTL (Arabic)
First Button (Thumbs Up)
Last Button (More ...)

[chrisbobbe]

Thanks, this looks great! Marking for Greg's review.

I guess the ">" icon on the "more" button should really be flipped into "<" in RTL. Let's leave that out of scope for this PR, though. It's an instance of #1907.

[yash-agarwa-l]

Thanks for the review!
I noticed that too. Since it's out of scope here, I've just submitted a separate PR for this. (edit: #2015)

[chrisbobbe]

I've just submitted a separate PR for this

Thank you! I've edited your comment so it links to that PR, #2015, to make it easy to find from here.

[gnprice]

Thanks! This looks great, with just small nits in the code style. Please go ahead and fix these and then I'll be glad to merge.

[gnprice]

nit: Let's inline textDirection:

Suggested change

	? const BorderRadiusDirectional.only(topStart: Radius.circular(7)).resolve(textDirection)
	? const BorderRadiusDirectional.only(topStart: Radius.circular(7))
	.resolve(Directionality.of(context))

That means the lookup only happens in the case where it's needed. It's also hardly any longer on this line.

[gnprice]

nit: this puts important information past column 80; add a line break:

Suggested change

	borderRadius: const BorderRadiusDirectional.only(topEnd: Radius.circular(7)).resolve(textDirection),
	borderRadius: const BorderRadiusDirectional.only(
	topEnd: Radius.circular(7)).resolve(textDirection),

(Could also inline textDirection the same as in the other place; but here that doesn't matter behavior-wise because it's needed unconditionally anyway.)

[yash-agarwa-l]

Great point, that avoids an unnecessary lookup. Thanks! Applied.

[gnprice]

Thanks! Looks good; merging, after fixing one nit below.

[gnprice]

nit: indentation

Suggested change

	? const BorderRadiusDirectional.only(topStart: Radius.circular(7))
	.resolve(Directionality.of(context))
	? const BorderRadiusDirectional.only(topStart: Radius.circular(7))
	.resolve(Directionality.of(context))

[gnprice]

Also fixed what appears to be a missing word in the commit message:

-    We now use  and resolve it against the
+    We now use `BorderRadiusDirectional` and resolve it against the
     context's text direction to ensure the correct corners are rounded
     regardless of layout direction.