Implementation of hostname conformance in peering connections is incorrect.

#### Overview of the Issue

The dialog box that appears when creating a new peering token says the following:

```
Must be a valid DNS hostname. Must contain 1-64 characters (numbers, letters, and hyphens), and must begin with a letter. Once created, this cannot be changed.
```

Note that it enforces no constraints on the ending character. This is in-line (sort-of) with the description of a valid hostname as per RFC952 and its subsequent errata. When attempting to submit the new peer, a new error shows up with additional constraints:

```
consul-example1 is not a valid peer name: a valid peering name must consist of lower case alphanumeric characters or '-', and must start and end with an alphanumeric character.
```

---

#### Reproduction Steps

Attempt to create a consul peering token with a hostname that ends with a number.

### Consul info for both Client and Server

Verified on v1.16.0 on Debian amd64.