Need EventToAxisArray unit

[cboulay]

ezmsg.blackrock sends out its spike events as a smattering of EventMessage objects. These need to be wrangled into a common message for most processing methods.

A unit that is parameterized with a desired (e.g.) output_rate = 30_000. could construct a pydata.sparse buffer with "time" axis .gain of 1 / output_rate seconds. As events arrive, they are placed into this buffer and update self.last_write_time_idx.

A separate @ez.publisher task will grab a block from the buffer from last_read_time_idx until 1 frame before self.last_write_time_idx, update last_read_time_idx, then put the block into an AxisArray message and yield it.