SDK-6120: Add image corner radius and border support across push templates

[reshab-code]

Summary

• Adds support for pt_img_corner_radius (0-32 ), pt_img_border_width (0-8 ), and pt_img_border_clr across all image-bearing push templates.
• Applies to Carousel, ZeroBezel, VerticalImage, Timer, Rating, ProductDisplay (Linear + Vertical), ContentSlider, SingleMedia, and the shared CTCaptionedImageView.
• Introduces a shared CTUtiltiy.applyImageStyling helper that clamps values and applies layer.cornerRadius / layer.borderWidth / layer.borderColor.
• No-ops on small icons and product display small images. VerticalImage defaults to its existing 8 dp corner radius when the key is absent.
• Values are clamped at both the ObjC entry point (CTNotificationViewController) and the Swift utility layer.

Test plan

• Verify corner radius renders correctly at boundary values (0, 16, 32) on Carousel, ZeroBezel, Timer, Rating, and VerticalImage templates.
• Verify border width + color renders correctly; confirm absent/zero values produce no visible border.
• Verify VerticalImage retains its default 8 dp corner radius when pt_img_corner_radius is not sent.
• Verify ProductDisplay small images are unaffected by border/radius keys.
• Verify GIF static fallback frames receive styling; animated playback is unaffected.
• Confirm no regressions on templates when all three keys are absent (legacy payloads).

[shubhambjadhavar]

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