mgr/dashboard: Use human readable units on the OSD I/O graphs
Currently, the OSD datatable provides two columns "Read bytes" and "Write bytes" and embedded charts that indicate the current rate in a tooltip when moving the mouse over individual points of the charts. However, the amount of data is displayed in "bytes", which is hard to read and convert.
Instead, these byte values displayed in the tooltips should be converted to human-readable units (e.g. kiB, MiB, TiB) and the column headers should be renamed to "Reads" and "Writes".