Use the admin api instead of the import functionality

[nirinchev]

Description

This replace the import/export approach with using the admin API to configure BaaS apps. It's intended to prepare us for FLX where the import is not wired up yet.

TODO

• Changelog entry
• Tests (if applicable)

[coveralls]

Pull Request Test Coverage Report for Build 1692620183

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 549 unchanged lines in 29 files lost coverage.
• Overall coverage decreased (-7.7%) to 74.632%

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Files with Coverage Reduction	New Missed Lines	%
Realm/Realm/Extensions/TaskExtensions.cs	1	81.25%
Realm/Realm/Realm.cs	2	90.73%
Realm/Realm/Helpers/SerializationHelper.cs	3	18.31%
Realm/Realm/Native/AppError.cs	3	0%
Realm/Realm/Sync/UserIdentity.cs	3	0%
Realm/Realm/Handles/AppHandle.EmailPassword.cs	4	8.33%
Realm/Realm/Native/StringStringPair.cs	4	0%
Realm/Realm/Native/UserApiKey.cs	4	0%
Realm/Realm/Native/Credentials.cs	6	0%
Realm/Realm/Sync/ProgressNotifications/SyncProgress.cs	6	0%

Totals
Change from base Build 1688124756:	-7.7%
Covered Lines:	4600
Relevant Lines:	6150

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💛 - Coveralls

[papafe]

It's a little dense to follow everything, but it seems to make sense

[fealebenpae]

It looks okay , but I believe as it is written it'll only work when running against local (aka docker) baas, and not Atlas, because of how URLs are hardcoded in CreateApp. I misread the service config, it does support Atlas clusters for sync.
Also I think we might want to look at System.CommandLine when we do introduce the ability to test against an Atlas cluster.