Make DefaultLUTService use IOService

[stelfrich]

DefaultLUTService.legacyTextLUT uses TableLoader.valuesFromTextFile to read a LUT from a CSV files. Since this is the only use of TableLoader.valuesFromTextFile in our codebase we should retire it in favor of implementations in scijava-plugins-io-table. See also scijava/scijava-plugins-io-table#4 (comment).

This, however, poses several challenges/tasks (in no particular order):

1. Should LUTService still support reading of LUTs from InputStream? If so, such requests can't be handled by IOService. Is that correct, @ctrueden?
2. We should migrate code for reading LUTs from InputStreams into dedicated IOPlugins
3. Basically, strip down the LUTService to pass requests to IOService and fail gracefully if a LUT can't be read (which doesn't work for InputStreams - see 1.)

[ctrueden]

Should LUTService still support reading of LUTs from InputStream? If so, such requests can't be handled by IOService.

The plan is to improve IOPlugin to support using Location as well as String, so that we can still support streams and remote locations and whatever extensibly via a common mechanism. I think we can do it in a backwards-compatible way.

CC @gab1one