Do not override user defined event functions

[roydukkey]

It is not currently possible for the consumer to define their own onGridReady, onCellValueChanged, onSelectionChanged since they are override by the onMount functionality.

svelte-ag-grid/src/Component.svelte

Lines 49 to 58 in 9d19c4c

	onMount(() => {
	grid = new Grid(ref, {
	...options,
	columnDefs,
	rowData: data,
	onGridReady,
	onCellValueChanged,
	onSelectionChanged,
	});
	});

I think it would be find to assume that over event's should fire before any user defined events, so I would propose this solution, implement similarly for all three events.

let consumerOnGridReady;

const onGridReady = (params) => {
	api = grid.gridOptions.api;
	if (loading) api.showLoadingOverlay();
	if (consumerOnGridReady) consumerOnGridReady(params);
};

onMount(() => {
	if (options.onGridReady) {
		consumerOnGridReady = options.onGridReady;
	}

	grid = new Grid(ref, {
		...options,
		columnDefs,
		rowData: data,
		onGridReady,
		onCellValueChanged,
		onSelectionChanged,
	});
});

[roydukkey]

Here's a working branch for this: master...roydukkey:issue/9.

I know this adds more complexity to the wrapper, which is intended to be lightweight, so if this is undesired, I'll keep this on my fork otherwise, I'll submit a PR.

Also, note that I have changed how the api field is recorded. Accessing the event rather than the grid's grid options should be slightly quicker.