Choosing an encoding does not affect the display of a row key

**Is your feature request related to a problem? Please describe.**
I need to view data that is in bytes. cloud-bigtable-cbt-cli recently merged a PR (https://github.com/googleapis/cloud-bigtable-cbt-cli/pull/28) that allowed a user to specify the encoding used when displaying byte data. This allows me to properly view the column values, but unfortunately the row key is still encoded in what I believe is UTF-8.

**Describe the solution you'd like**
I would love to be able to display the column values and the row key with the same encoding.

**Describe alternatives you've considered**
I've considered making a separate CLI tool that takes a row key and displays the data however I want, but the team loves CBT CLI for all of its other features and does not want to be switching back and forth between a custom CLI tool and CBT CLI.

**Additional context**

As you can see I can correctly read the column data, but row key (B?G???A?'?8???K?) isn't legible.