Added some new Features

[danielpastoor]

I added some new features.

Features:
1.
Check if a site exists by alias and full url
2.
Added option to create a team site when you use "Application" permissions.
3.
Changed TeamChannelTabConstants.cs location from internal to public so people can use it in there own projects.

[codecov-commenter]

Codecov Report

Merging #859 (5ed8270) into dev (63545f3) will increase coverage by 0.97%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##              dev     #859      +/-   ##
==========================================
+ Coverage   82.42%   83.39%   +0.97%     
==========================================
  Files         416      559     +143     
  Lines       28590    36271    +7681     
==========================================
+ Hits        23565    30248    +6683     
- Misses       5025     6023     +998     

Impacted Files	Coverage Δ
...re/Model/SharePoint/Changes/Internal/ChangeUser.cs	0.00% <0.00%> (-100.00%)	⬇️
...k/PnP.Core/Model/Teams/Internal/TeamChatMessage.cs	72.34% <0.00%> (-27.66%)	⬇️
.../PnP.Core/Model/SharePoint/Core/Internal/Folder.cs	73.28% <0.00%> (-23.89%)	⬇️
...odel/Security/Internal/SharePointUserCollection.cs	78.78% <0.00%> (-21.22%)	⬇️
....Core/Exceptions/MicrosoftGraphServiceException.cs	80.00% <0.00%> (-20.00%)	⬇️
...PnP.Core.Admin/Model/Teams/Internal/TeamCreator.cs	76.19% <0.00%> (-14.29%)	⬇️
src/sdk/PnP.Core/Services/Core/TestManager.cs	54.94% <0.00%> (-12.96%)	⬇️
.../Model/SharePoint/Core/Internal/SharePointAdmin.cs	81.06% <0.00%> (-12.80%)	⬇️
.../SharePoint/Core/Internal/ContentTypeCollection.cs	87.67% <0.00%> (-12.33%)	⬇️
...e/Model/Teams/Internal/TeamChannelTabCollection.cs	87.92% <0.00%> (-12.08%)	⬇️
... and 232 more

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[jansenbe]

Thanks for the contributions @danielpastoor 💪

[jansenbe]

Thanks for the PR @danielpastoor . I've merged this one, but did do quite some changes, maybe you want to have a look at 0deb3db to understand what I've changed. Key changes are:

• some simplification: a method does one thing, creating a team site via creating a group is fine, in that same method also trying to create a Team is too much
• Removed some overloads
• Added missing sync method
• Moved around some the SiteExists methods
• From a coding style we always wrap a block in braces, so the if (condition) then do x has been updated to if (condition) then { do x }

But please don't get me wrong here, super happy to these contributions come in as they add value for folks using the SDK. Taking in account above recommendations will help speed up merging of future PRs :-)

[danielpastoor]

@jansenbe Thank you for the feedback. I see this as a learning curf for me. And I will improve the my coding for the next time. Thanks