[Feature]用户自定义比较函数来判断cell是否可以合并

[godnotking]

What problem does this feature solve?

在设置autoMerge的时候，用户可以自定义比较函数来判断cell是否可以合并，自定义复杂类型的相等性

What does the proposed API look like?

{
        "field": "Category",
        "title": "Category",
        "width": "auto",
        "mergeCell": true,
        "mergeEqualFunc":(cellA, cellB)=>{
        return cellA.id === cellB.id
        }
        
    },