Allow quiet load and unset targets by number

Could you please add an option for script to not ask for targets to modify and proceed silently?

Current usage:
```
user$ proxyman load MyProxy
```
then you choose from targets to modify.

Feature request:
```
user$ proxyman load MyProxy **1**
user$ proxyman unset **1**
```

In this case the script will automatically unset provided profile number

Start with the CLI entry points for `load` and `unset`, using the examples in the issue to trace how targets are currently selected. Done means a numeric target can be supplied to either command and the script proceeds without prompting; no file or test is named in the issue.

Written by the indexing model from the issue text.