Fix #1303: Remove placeholder from TextField in v0.9 Angular and add to v0.10 spec

[josemontespg]

What

Removed support for the placeholder property in the v0.9 Angular implementation of the TextField component, and added it to the v0.10 specification.

Why

The placeholder property was supported in the Angular renderer but was missing from the v0.9 spec. To achieve consistency for v0.9, it was removed from the renderer. However, since it maps directly to an HTML attribute and is essential for TextField, it was decided to add it to the upcoming v0.10 specification.

[gemini-code-assist]

Code Review

This pull request removes the placeholder binding and its corresponding computed property from the Angular TextFieldComponent in version 0.9, while adding the placeholder property to the version 0.10 JSON specification. The review feedback recommends removing the resulting blank lines in both the component template and the class definition to maintain code cleanliness and consistency.

[gemini-code-assist]

The removal of the [placeholder] binding leaves an unnecessary blank line within the <input> tag. It is better to remove this line to maintain clean template syntax.

Suggested change

	(input)="handleInput($event)"
	[placeholder]="placeholder()"
	[class.invalid]="props()['isValid']?.value() === false"
	(input)="handleInput($event)"
	[class.invalid]="props()['isValid']?.value() === false"

[gemini-code-assist]

The removal of the placeholder computed property leaves an unnecessary blank line. Since other property declarations in this class (like label and value) are not separated by newlines, this should be removed for consistency.

Suggested change

	readonly value = computed(() => this.props()['value']?.value() || '');
	readonly placeholder = computed(
	() => (this.props() as AnyDuringSchemaAlignment)['placeholder']?.value() || '',
	);
	readonly variant = computed(() => this.props()['variant']?.value());
	readonly value = computed(() => this.props()['value']?.value() || '');
	readonly variant = computed(() => this.props()['variant']?.value());