[kolsha]

Issue #, if available: N/A

Description of changes:

Make Aws::Http::HttpClient::RetryRequestSleep(std::chrono::milliseconds) virtual so custom HTTP clients can override retry delays. The default sleep implementation stays the same.

Restore the repository-wide spelling check by correcting comment typos and resolvedIdentity, and adding existing CMake, Windows API, and imported AIX identifiers to the dictionary. No files or spelling checks are disabled.

Validation:

• git diff --check: passed.
• Full workflow cspell scope: all 542 files passed locally with zero issues.
• No full SDK build or runtime tests run. The existing Build SDK job fails before compilation: the fork cannot assume the configured AWS infrastructure role (sts:AssumeRoleWithWebIdentity). This workflow is unchanged by this PR.

Check all that applies:

• Did a review by yourself.
• Added proper tests to cover this PR. The spelling fixes are validated by the full cspell check; no new runtime tests were added for the virtual declaration.
• Checked if this PR is a breaking (APIs have been changed) change. Adding a virtual method changes the vtable layout; rebuild the SDK and its consumers together.
• Checked if this PR will not introduce cross-platform inconsistent behavior.
• Checked if this PR would require a ReadMe/Wiki update. None needed.

No full SDK platform builds performed.