Add validation of encryption key length and method

[acelyc111]

Before this patch, there is no validation of the encryption key length
and method, so if using an encryption method but with a not matched length
encryption key, it would cause encrypt and decrypt not match bug.

This patch fixes this bug and adds some related modifacations, including:

• Add validation of encryption key length and method
• Use RegisterOptions to initialize the AESEncryptionProvider objects
  instead of AddFactory
• Still keep AddFactory to create AESEncryptionProvider objects
• The AddFactory will only create AESEncryptionProvider objects successfully
  when the uri match AES
• Remove the unit tests added in previous patched, we can use the enviroment
  variables instead, say TEST_FS_URI and ENCRYPTED_ENV
• Remove the new add gflags in db_bench tool, we can use --fs_uri instead
• Add more unit tests in encryption/encryption_test.cc
• Add or update related CI jobs build-linux-encrypted_env-openssl*

The functionality can be checked by the following script as well.

#!/usr/bin/env bash

set -ex

# 1. build
mkdir build && cd build
cmake -DWITH_LZ4=1 -DCMAKE_BUILD_TYPE=Debug -DWITH_TESTS=1 -DROCKSDB_BUILD_SHARED=0 -DWITH_OPENSSL=1 ..
make -j32

uris=("provider={id=AES;hex_instance_key=0123456789ABCDEF0123456789ABCDEF;method=AES128CTR};id=EncryptedFileSystem"
      "provider={id=AES;hex_instance_key=0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF;method=AES192CTR};id=EncryptedFileSystem"
      "provider={id=AES;hex_instance_key=0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF;method=AES256CTR};id=EncryptedFileSystem"
      "provider={id=AES;hex_instance_key=0123456789ABCDEF0123456789ABCDEF;method=SM4CTR};id=EncryptedFileSystem")
for uri in ${uris[*]}; do
  echo "${uri}"

  # Set env (select 1 of the 4)
  export TEST_FS_URI=${uri}

  # Run unit tests
  ./env_basic_test --gtest_filter=*CustomEnv*
  ./env_test --gtest_filter=CreateEnvTest.CreateEncryptedFileSystem

  # Run benchmarks
  ./db_bench --fs_uri="${uri}" --benchmarks="fillseq,readrandom,readseq" --compression_type=lz4 --num=1000000

  # Run ldb tools
  ./tools/ldb --fs_uri="${uri}" --db=/tmp/rocksdbtest-1000/dbbench/ put k v
  ./tools/ldb --fs_uri="${uri}" --db=/tmp/rocksdbtest-1000/dbbench/ get k
  ls -l /tmp/rocksdbtest-1000/dbbench | grep "log" | awk '{print $NF}' | xargs -i ./tools/ldb --fs_uri="${uri}" dump_wal --walfile=/tmp/rocksdbtest-1000/dbbench/{} | head
  ./tools/ldb --fs_uri="${uri}" --db=/tmp/rocksdbtest-1000/dbbench/ scan --hex | head
  ./tools/ldb --fs_uri="${uri}" --db=/tmp/rocksdbtest-1000/dbbench/ dump --hex | head
  ./tools/ldb --fs_uri="${uri}" --db=/tmp/rocksdbtest-1000/dbbench/ manifest_dump | head
  ./tools/ldb --fs_uri="${uri}" --db=/tmp/rocksdbtest-1000/dbbench/ list_live_files_metadata | head
done

# Unset the env
unset TEST_FS_URI