Remove FormatTools use

The rasterToPosition methods unnecessarily duplicate IntervalIndexer
functionality. This also reduces direct SCIFIO reliance.
Remove SCIFIO import from test

LegacyUtilsTest does not need to depend on SCIFIO. It's just using
convenient additional axis names. We can use custom axes instead.
Add reminders to remove SCIFIO references

Our goal is to migrate some of the image-related metadata interfaces
from SCIFIO to imagej-common. Then we will be able to completely remove
the SCIFIO dependency from imagej-legacy.