Builds upon https://github.com/coder/coder/pull/19970
I got kinda carried away when I saw the extra stuff we could add in
here, so I went ahead and added it:
* User ID
* Organization IDs
* Roles
This technically duplicates functionality from `coder users show` but I
figure folks may find it useful.
This addresses a long-standing gripe of mine: to get your logged in
username you would have to do
```bash
coder whoami | awk '{print $9}'
```
This allows you to do:
```
coder whoami -o json | jq -r '.username'
```
or
```
coder whoami -f table -c username
```
Cian Johnston