[Feature] connectNulls strict mode that ignores undefined

### Version

5.4.1

### Link to Minimal Reproduction

https://echarts.apache.org/examples/en/editor.html?c=line-simple&code=PYBwLglsB2AEC8sDeAoWsCeBBAHhAzgFywDaa6y5FsYGIApsQOQBuAhgDYCu9TANFQoBbCNGIAGAdXRC2OYgGYp0wQF9yAXWU5cBYmWqppNOo1hNIQ3svTr0W8h3oBzetAAmxIxXwALYADuxABmnPj05KrKzgBOEJ7IUeRgwMAckCBeSejhcfREpILe1LQMzByi1oLo0GxWzO5sYGwAjPzVsADGMND0nWAAclwcHAWho_Q2FG7d7mbF0vLmGPRsMe3G6BgNTa1MHXYU2RQL6KVmTBW9G9K19eaNzQBMN9Td0L39QyNjYZMd6BmwDmXgBsCWTBWa1e0m2D12LwOak0ykebHCYH0RQ67ggVmg-CgBP0kNW6z48OabQpTDRLwcxnwwC4MU6ZgMm1OsLJzCe4ha4hhxlpuzaxBaU2FdKYxCeYOOxi51ChMV5_OpYPQIqpMtg0GGHEl0m1bBesqNtgtlE2FBVapaLytWrRYtgEs1sAA9J7YHTYH5mRx3HrgGBYL42Cx6LA2LBnGwQOH6DF6AB-eVWpW2nnmPktBRC40u3Xum3OhG6p5WhUUDTI-wCVQAbiAA

### Steps to Reproduce

dataset with data missing on some dimension

### Current Behavior

nulls and undefined are treated the same

### Expected Behavior

dataset with nulls should have gaps, dataset with undefined should not have gaps. connectNulls should connects null, not undefined. maybe add connectNulls: 'strict' for this behaviour?

### Environment

_No response_

### Any additional comments?

I'm using series.data at the moment and was testing dataset so I can have just one data object, but some sensors send data on different intervals so they are missing from some "rows". At the moment I'm just creating per series data that we have. Can't use connectNulls since I wan't the line to have gaps if I filter something out and put a null there. (like filter out weekends)