DataTable's filterButtonProps prop should accept a partial

[FloEdelmann]

DataTable's filterButtonProps prop has type DataTableFilterButtonPropsOptions. But in the implementation, it actually deals with partial objects (Partial<DataTableFilterButtonPropsOptions>), to allow users to only overwrite some of the buttons:

primevue/packages/primevue/src/datatable/DataTable.vue

Lines 2070 to 2085 in 462a029

	headerFilterButtonProps() {
	return {
	filter: { severity: 'secondary', text: true, rounded: true },
	...this.filterButtonProps,
	inline: {
	clear: { severity: 'secondary', text: true, rounded: true },
	...this.filterButtonProps.inline
	},
	popover: {
	addRule: { severity: 'info', text: true, size: 'small' },
	removeRule: { severity: 'danger', text: true, size: 'small' },
	apply: { size: 'small' },
	clear: { outlined: true, size: 'small' },
	...this.filterButtonProps.popover
	}
	};

The prop type should reflect that, see PR #7247.