Function abbreviate

abbreviate(hex: string): string
Shorten a hex id or key to a recognisable prefix.
Parameters
- hex: string
  A 64-hex id or public key.
Returns string
The first eight characters and an ellipsis.
Example
```
abbreviate('3bf0c63fcb93463407af97a5e5ee64fa883d107ef9e558472c4eb9aaaefa459d'); // '3bf0c63f…'
```