[material_ui] Migrate M3 ActionChip template to use new gen_defaults

[elliette]

Work towards flutter/flutter#187899
Fixes flutter/flutter#188396

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Test exemption: Template migration PR.

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[gemini-code-assist]

Code Review

This pull request updates the Action Chip defaults generation logic by migrating to a new template structure and utilizing specific token constants from 'assist_chip.dart'. It includes a new 'border' helper method in 'TokenTemplate' and updates the 'gen_defaults.dart' script to include the 'ActionChipTemplateM3'. Feedback identified two missing opacity applications for disabled states in the label and icon colors, which require updates to ensure consistency with the token data.

[gemini-code-assist]

The disabled label color is missing its opacity. According to the token data in assist_chip.dart, disabledLabelTextOpacity should be applied to the color for the disabled state.

Suggested change

	: ${color(TokenAssistChip.disabledLabelTextColor, colorSchemePrefix)},
	: ${colorWithOpacity(TokenAssistChip.disabledLabelTextColor, TokenAssistChip.disabledLabelTextOpacity, colorSchemePrefix)},

[gemini-code-assist]

The disabled icon color is missing its opacity. According to the token data in assist_chip.dart, withIconDisabledIconOpacity should be applied to the color for the disabled state.

Suggested change

	: ${color(TokenAssistChip.withIconDisabledIconColor, colorSchemePrefix)},
	: ${colorWithOpacity(TokenAssistChip.withIconDisabledIconColor, TokenAssistChip.withIconDisabledIconOpacity, colorSchemePrefix)},

[QuncCccccc]

LGTM! Thanks!

nit: Maybe we can add a test to verify something like class name has suffix "M3".