NIFI-8501: Setup Azure blob client side encryption

[gschaer]

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Description of PR

Adds Azure blob client side encryption (symmetric only). Fixes NIFI-8501.
Also fixes NIFI-8508 by incrementing the amount of time the thread is sleeping when doing the integration testing.

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[jfrazee]

Reviewing

[jfrazee]

@gschaer Thanks for the work on this. I went through and tested all the functionality. In addition to the code comments I have a few other things:

1. Right now if the encryption type is NONE and a key id and key are specified the configuration is valid. It doesn't encrypt the files as expected, but I think this is confusing. I'd say it's more typical to mark cases like that as invalid.
2. The azure.length property reflects the encrypted object length and not the decrypted length. I've seen similar situations cause problems. This makes me think it could be useful to add an attribute that specified whether it was encrypted so there's some indicator that some of the metadata might not match.
3. I think it might be useful to add something to an additionalDetails.html file to explain more about the behavior or how to create the keys.

[jfrazee]

Should any of this be moved to the AbstractAzureBlobStorageIT? (In which case, already existing tests would need to be updated too.)

[gschaer]

This is a tricky one... It would require complex rewrite of all these tests.

[jfrazee]

@gschaer Thanks for the changes. I tested the put and fetch with and without CSE, ran the ITs, and tested an upgrade. LGTM. Will merge shortly.