Batch: support data split to reduce transmission bubble

[klin02]

Previously, we view data collected from same cycle as a whole, end batch assembling when step data longer than available space. It results in bubble in transmission, and cannot handle situation when step data longer than Max width in a single transmission.

This change support spliting step data according to collector, appending part of data to output and updating remained to state. To shorten logic length, we divide complex logic to three stage.

Note step data may be splited to different batch func, and should be read as a whole, so we avoid buffer-zone switch when batch enabled.