Detect GCM-SIV alignment change

[justsmth]

Issues:

N/A

Description of changes:

• When using GCM-SIV, changing the location of an EVP_AEAD_CTX struct to a different 8-byte alignment can cause a silent failure resulting in data corruption.
• This change triggers a failure when an unsupported alignment change is detected.

Call-outs:

N/A

Testing:

• Added tests to verify that encryption fails in this scenario.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license and the ISC license.