👹 Add `gridController.compress()` method and `autoCompress` prop

[cuire]

Closes #57

Breaking

Grid with collision = "compress" now auto compress its when items are changed programmaticly. If you want to disable this behavior, you can set autoCompress prop to false.

Added gridController.compress() method

gridController.compress() can be used to compress items on grids with non compress collision strategy.

<script lang="ts">
    import Grid, { GridItem, type GridController } from 'svelte-grid-extended';

    let items = [
        { id: '1', x: 0, y: 0, w: 2, h: 5 },
        { id: '2', x: 2, y: 2, w: 2, h: 2 }
    ];

    let gridController: GridController;

    function compressItems() {
        gridController.compress();
    }

    const itemSize = { height: 40 };
</script>

<button class="btn" on:click={compressItems}>Compress Items</button>

<Grid {itemSize} cols={10} collision="push" bind:controller={gridController}>
    {#each items as item (item.id)}
        <GridItem id={item.id} bind:x={item.x} bind:y={item.y} bind:w={item.w} bind:h={item.h}>
            <div class="item">{item.id.slice(0, 5)}</div>
        </GridItem>
    {/each}
</Grid>