[cupertino_ui] Add SemanticsRole.slider to CupertinoSlider

[hannah-hyj]

Adds SemanticsRole.slider, minValue, and maxValue to Slider semantics.

issue: flutter/flutter#184030

blocked by flutter/flutter#184029

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[gemini-code-assist]

Code Review

This pull request updates CupertinoSlider to include SemanticsRole.slider and the min and max bounds in its semantics configuration, passing these properties down to the underlying render object and updating the associated tests. The review feedback identifies a type mismatch where minValue and maxValue are incorrectly assigned and tested as String values instead of double values.

[gemini-code-assist]

In Flutter's SemanticsConfiguration, minValue and maxValue are of type double?, not String?. Assigning a String (via toString()) will cause a compile-time type mismatch error. They should be assigned directly as double values.

Suggested change

	config.minValue = min.toString();
	config.maxValue = max.toString();
	config.minValue = min;
	config.maxValue = max;

[gemini-code-assist]

Since minValue and maxValue are double values, they should be matched as double literals rather than strings in matchesSemantics.

Suggested change

	minValue: '0.0',
	maxValue: '1.0',
	minValue: 0.0,
	maxValue: 1.0,

[gemini-code-assist]

Since minValue and maxValue are double values, they should be matched as double literals rather than strings in matchesSemantics.

Suggested change

	minValue: '0.0',
	maxValue: '1.0',
	minValue: 0.0,
	maxValue: 1.0,

[gemini-code-assist]

Since minValue and maxValue are double values, they should be matched as double literals rather than strings in matchesSemantics.

Suggested change

	minValue: '0.0',
	maxValue: '1.0',
	minValue: 0.0,
	maxValue: 1.0,

[gemini-code-assist]

Since minValue and maxValue are double values, they should be matched as double literals rather than strings in matchesSemantics.

Suggested change

	minValue: '0.0',
	maxValue: '1.0',
	minValue: 0.0,
	maxValue: 1.0,