add multiple features

[DanielHabenicht]

Hi there @timetheoretical, thanks for developing this plugin.

I am a colleague of fmuscetra.
We upgraded the Plugin a fair bit and I wanted to share what we've done.

I tried to make all changes as adaptive as possible so it can be reused in public.

Here they are:

Breaking:
Changed the .dll and Registry Entries to not contain spaces anymore. ("Jitsi Meet Outlook Add-In" => "JitsiMeetOutlookAddIn").
(There was an issue with Spaces at our side :D)

Enhancements:

• Add Phone Numbers (from the Jitsi Installation pointed to) Dial-in phone number options when using default meet.jit.si server #28
• Use Conference PIN (from the Jitsi Installation pointed to, instead of manually generated) (so that any algorithm can be used)
• Add optional Conference Scheduler to plan meetings ahead of time on the jitsi server side
• Add Button to add Jitsi Conference in normal meetings Support for New Meeting Ribbon #38 Would it be possible to add a jitsi link in an existing "regular" meeting. #22
• Enable modification of already saved/closed meetings

I don't have much time from work to split this up into multiple PRs. So I am sorry for it being so big.

[timetheoretical]

Hey @DanielHabenicht and @fmuscetra , thanks a lot for this -- really nice work!

I will accept this into the main branch. However, I will only be able to write update notes and generate new installer files in August.