Improve Dropdown implementation for Accessibility

[mertsincan]

Dropdown's codebase has been completely overhauled and is now closer to spec. In addition, some extra changes were made to the design based on user feedback.
https://w3c.github.io/aria-practices/examples/combobox/combobox-select-only.html
https://www.w3.org/WAI/ARIA/apg/example-index/combobox/combobox-select-only.html

Added Properties:

• InputStyle: Inline style of the input field
• inputClass: Style class of the input field
• inputProps: Uses to pass all properties of the HTMLInputElement/HTMLSpanElement to the focusable input element inside the component
• panelStyle: Inline style of the overlay panel
• panelProps: Uses to pass all properties of the HTMLDivElement to the overlay panel inside the component.
• filterInputProps: Uses to pass all properties of the HTMLInputElement to the filter input inside the component.
• clearIconProps: Uses to pass all properties of the HTMLElement to the clear icon inside the component.
• autoOptionFocus: Whether to focus on the first visible or selected element when the overlay panel is shown.
• filterMessage: Text to be displayed in hidden accessible field when filtering returns any results. Defaults to value from PrimeVue locale configuration.
• selectionMessage: Text to be displayed in hidden accessible field when options are selected. Defaults to value from PrimeVue locale configuration.
• emptySelectionMessage: Text to be displayed in hidden accessible field when any option is not selected. Defaults to value from PrimeVue locale configuration
• ariaLabel: Defines a string value that labels an interactive element.
• ariaLabelledby: Identifier of the underlying input element.

Removed Properties:

• ariaLabelledBy: Use ariaLabelledby instead