Amended environment variable naming
In order to play better with localstack, local-kms specific environment variables are now prefixed with KMS_
.
Specifically:
- KMS_ACCOUNT_ID
- KMS_REGION
- KMS_SEED_PATH
- KMS_DATA_PATH
This version remains backwards compatible, with the original naming still being accepted, but a deprecated warning is now shown. The old naming will be removed in v4.