Put sha256 context init/shutdown under a RAII wrapper

[maxtropets]

Because why not?..

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Do not merge before:

• Confirm perf OK

[Copilot]

Pull Request Overview

This PR introduces a RAII wrapper (Sha256ContextGuard) to replace manual initialization and cleanup calls for the OpenSSL SHA256 context management, improving resource safety and reducing boilerplate code.

• Replaced manual ccf::crypto::openssl_sha256_init() and ccf::crypto::openssl_sha256_shutdown() calls with RAII pattern
• Added Sha256ContextGuard class that handles initialization in constructor and cleanup in destructor
• Updated documentation to reflect the new API usage pattern

Reviewed Changes

Copilot reviewed 28 out of 28 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
include/ccf/crypto/openssl_init.h	Defines new Sha256ContextGuard RAII wrapper class
src/crypto/openssl/hash.cpp	Implements the guard constructor/destructor and improves error handling
tests/perf-system/submitter/submit.cpp	Migrates from manual init/shutdown calls to RAII guard
src/pal/test/snp_ioctl_test.cpp	Migrates test code to use the new RAII pattern
src/pal/test/snp_attestation_validation.cpp	Migrates test code to use the new RAII pattern
src/node/test/*	Multiple test files migrated to use the RAII pattern
src/kv/test/*	Multiple test files migrated to use the RAII pattern
src/indexing/test/indexing.cpp	Migrates test code to use the RAII pattern
src/host/test/ledger.cpp	Migrates test code to use the RAII pattern
src/host/run.cpp	Migrates main application code to use the RAII pattern
src/enclave/enclave.h	Migrates enclave initialization to use the RAII pattern
src/crypto/test/*	Multiple crypto test files migrated to use the RAII pattern
doc/build_apps/get_started.rst	Updates documentation to reflect new API usage
CHANGELOG.md	Documents the API change

Comments suppressed due to low confidence (1)

src/node/test/history_bench.cpp:1

• This line should call openssl_sha256_shutdown() instead of openssl_sha256_init(). The original code had a shutdown call here, but the replacement is incorrect.

// Copyright (c) Microsoft Corporation. All rights reserved.

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