Extract ranges from pure dates

Extract range from pure dates (date without time) for commands which require it:
```
2018 - whole year: 2018-01-01T00:00:00 - 2019-01-01T00:00:00
2018-10 - whole month: 2018-10-01T00:00:00 - 2018-11-01T00:00:00
2018-10-03, 20181003 - whole day: 2018-10-03T00:00:00 - 2018-10-04T00:00:00
```

Start by tracing the CLI date parsing and range-handling entry points for commands that require a time range. Verify how year, year-month, and the two full-date formats are currently interpreted; done means each example expands to the stated start and exclusive end timestamps.

Written by the indexing model from the issue text.