Remove or move obsolete import operations

[magnesj]

Several import operations can now be removed or moved when the unified import of summary and grid is in place.

Main menu items to remove

• Create grid case group - RicCreateGridCaseGroupFromFilesFeature
• Create grid case ensemble - RicCreateGridCaseEnsemblesFromFilesFeature
• Import Eclipse cases recursively

These will be replaced by the unified import dialog.

Summary menu items to remove

All three ensemble/group menu items will be replaced with the unified import dialog.

Depending on #13696