[material_ui] Migrate M3 BottomSheet template to use new gen_defaults

[elliette]

Work towards flutter/flutter#187899
Fixes flutter/flutter#188404

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Test exemption: Template migration PR.

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[gemini-code-assist]

Code Review

This pull request migrates the Material 3 bottom sheet defaults to a generated part file using a new BottomSheetTemplateM3 template in the gen_defaults tool. The feedback suggests updating the constructor indentation in the template to match standard Dart formatting and using double literals for BoxConstraints to ensure consistency.

[gemini-code-assist]

For consistency with the constraints getter on line 48, and to explicitly use double literals for BoxConstraints parameters, use 640.0 instead of 640.

Additionally, updating the constructor's indentation to match the standard Dart style guide (which is what dart format produces) makes the template code cleaner and easier to maintain.

Suggested change

	$className(this.context)
	: super(
	elevation: ${number(TokenSheetBottom.dockedStandardContainerElevation)},
	modalElevation: ${number(TokenSheetBottom.dockedModalContainerElevation)},
	shape: ${shape(TokenSheetBottom.dockedContainerShape)},
	constraints: const BoxConstraints(maxWidth: 640),
	);
	$className(this.context)
	: super(
	elevation: ${number(TokenSheetBottom.dockedStandardContainerElevation)},
	modalElevation: ${number(TokenSheetBottom.dockedModalContainerElevation)},
	shape: ${shape(TokenSheetBottom.dockedContainerShape)},
	constraints: const BoxConstraints(maxWidth: 640.0),
	);

References

1. Code should follow the relevant style guides and use the correct auto-formatter (dart format for Dart). Aligning the template's formatting with the formatter's output ensures consistency and readability. ^(link)

[QuncCccccc]

LGTM