Create multiple offline calendars

[Rexadev]

Checklist

• I made sure that there are no existing issues - open or closed - to which I could contribute my information.
• I have read the FAQ and my problem isn't listed.
• I have taken the time to fill in all the required details. I understand that the feature request will be dismissed otherwise.
• This issue contains only one feature request.
• I have read and understood the contribution guidelines.

Describe the solution you'd like
Add option of adding calendar

1. I use Etar to create Offline Calendars and to Import/Export calendars (Online ones too).
   Would be nice to have this functionality in Simple-Calendar.

2. Etar show I have 1 offline calendar and 2 Google Synced Calendars but Simple Calendar at the bottom show I have 3 Calendars - 1. "Offline Calendar", 2. "Regular event", 3. An Offline Calendar I created on Etar .

Is your feature request related to a problem? Please describe.
Yes I want to use multiple calendars without needing 2 apps for it

Describe alternatives you've considered
Using Etar with this App

Additional context
None

### Related BUG

1 and 2 are empty
and Simple Calendar doesn't show Google Synced Calendars.

SimpleMobileTools/Simple-Calendar#1901

[Aga-C]

1. Please fill the template properly. These fields are to help structure your issue, so everybody can understand it properly,
2. Please report the related bug separately.

[Aga-C]

Please edit your template to make it look cleaner:

• move the Checklist section to the top
• move 1. and 2. points from the top to the Describe the solution you'd like section
• remove the related BUG section - this should be a separate bug report because it's not related to offline calendars

[RokeJulianLockhart]

#92 (comment)

Per SimpleMobileTools/Simple-Calendar#1901 (comment), shouldn't this feature already be available, @Rexadev?

[woheller69]

I would suggest to add it in CalDAV -> Manage synced calendars.

Add a Floating Action Button with a "+" there to add a new calender.
Add a context menu for long click on an existing calendar to delete it or to rename it