(CLI) Add -f short option for ivpn connect -fastest

[naltun]

PR type

What kind of change does this PR introduce?

This updates ivpn connect flag options.

I exclusively use the CLI to manage my IVPN connection and having the -f would be helpful. I can use this patch to compile locally, but I'm opening this PR in case it is useful.

• Feature

PR checklist

Please check if your PR fulfills the following requirements:

• I have read the CONTRIBUTING.md doc
• The Git workflow follows our guidelines: CONTRIBUTING.md#git
• I have added necessary documentation (if appropriate)

What is the current behavior?

To connect to the fastest server, the -fastest option is required.

Issue number: N/A

What is the new behavior?

Now the -f flag exists.

Here's a small demonstration:

Does this PR introduce a breaking change?

• Yes
• No

Other information