{Find} az find should support non-quoted input

It will be user-friendly to support non-quoted input in `az find`.

For example, this format works:

```sh
> az find "vm create"
Finding examples...

Here are the most common ways to use [vm create]:

Create an Azure Virtual Machine. (autogenerated)
az vm create --admin-password {admin-password} --admin-username deploy --image Centos --name MyVm --resource-group MyResourceGroup
...
```

But `az find vm create` fails:

```sh
> az find vm create
az: error: unrecognized arguments: create
usage: az [-h] [--verbose] [--debug] [--only-show-errors] [--output {json,jsonc,yaml,yamlc,table,tsv,none}] [--query JMESPATH] {find} ...
```

On the other hand, the Bash command `eval` and `echo` support such format:

```sh
$ echo hello world
hello world

$ eval echo hello world
hello world

$ eval ls /etc
NetworkManager ca-certificates.conf.dpkg-old dhcp host.conf ldap
```