Autofocus methods in scan and navigation don't match

Bug report

Summary

If running a scan with a medium or fine autofocus, the scan extension chooses 7 equidistant points separated by dz to measure sharpness. If running autofocus outside a scan using eV's navigation pane, only 5 points are used. For consistency, should scan only include 5 points range(-2 * autofocus_dz, 3 * autofocus_dz, autofocus_dz), or eV be updated to send :submit-data="{ dz: [-40, -20, -10, 0, 10, 20, 40] }", for example?

Steps to reproduce

In eV, run a fine or medium autofocus (5 z positions checked)

Run a 1x1x1 scan with autofocus set to fine or medium (7 z positions checked)

Additional details

I'd suggest that the most versatile fix would be to change the tile extension on the server to accept dz as a list (similar to the autofocus extension), moving any decisions about number of z positions to eV and allowing pyclient users more control over scans.

/cc @jtc42