Please provide CipherMode availability matrix

https://docs.microsoft.com/en-us/dotnet/api/system.security.cryptography.ciphermode?view=netcore-2.0

The current documentation does not show which cipher modes are supported by a certain algorithm on different platforms. One question I have is that "on which platforms is AES CFB mode fully supported?", that no existing documentation can tell.

Library authors and users are forced to rely on `CryptographicException` as stated, which is clearly inconvenient.

https://docs.microsoft.com/en-us/dotnet/api/system.security.cryptography.symmetricalgorithm.mode?view=netcore-2.0#System_Security_Cryptography_SymmetricAlgorithm_Mode

I know it is not easy to build a matrix in documentation, as there are multiple platforms, multiple algorithms and cipher modes to check. But I guess your test suite should cover the same things, so the information is already somewhere.

Only if you provide it, library authors and end users can then save tons of hours testing on their own.

Beginne mit der Durchsicht der verknüpften API-Dokumentation zu CipherMode und SymmetricAlgorithm.Mode und vergleiche anschließend deren Aussagen mit der Abdeckung von Plattformen, Algorithmen und Verschlüsselungsmodi in der Kryptografie-Testsuite. Als abgeschlossen gilt die Veröffentlichung einer dokumentierten Verfügbarkeitsmatrix, aus der hervorgeht, welche Modi jeder Algorithmus auf jeder Plattform unterstützt.

Vom Indexierungsmodell aus dem Issue-Text verfasst.