GisAssembly/GenerateMods may need better spec coverage

[ndushay]

(if we're not going to kill this code altogether ... See #707)

from https://codeclimate.com/github/sul-dlss/gis-robot-suite/lib/robots/dor_repo/gis_assembly/generate_mods.rb/source

it may be useful to add tests for

• geometry_type_ogrinfo of LineString (line 48)
• raster file_format without tif leads to 'ArcGrid' (lines 58-61) -- if we're still going to deal with ArcGrid ... see issue Convert ArcGrid to GeoTIFF #739
• find_geometry_type_ogrinfo with Geometry output (lines 79-83)

if those are all super-rare cases in actuality, shrug.

[aaron-collier]

Part of #707