Add new code examples for get/create secrets in Secrets Manager with C++ SDK

[OswaldHe]

aws-doc-sdk-examples Pull Request

Thank you for making a submission to the aws-doc-sdk-examples repository. For more information about submitting pull requests to this repository, see Guidelines for contributing.

NOTE: This PR template contains three sections. Depending on the reason for your pull request, please fill out the section that applies to you and then remove the other two sections.

New SDK Code Example

The submitter has:

• [x] Added the default copyright notice to all files.
• [ ] Created unit tests for all paths through the code and they all pass.
• [ ] Run a linter against all code and implemented the resulting suggestions.
• [x] Added minimum usage documentation as comments in the code.
• [x] Had comments and strings reviewed and incorporated suggested changes.
• [ ] Had the code reviewed and implemented the reviewer's suggested changes.

Resolve Issue

Issue #2669

Description of Changes

Please describe the changes you have made here.

• [ ] I have tested my changes and created unit tests for new code paths.
• [ ] Changes have been reviewed, and all reviewer comments have been incorporated.

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

[github-actions[bot]]

clang-tidy review says "All clean, LGTM! :+1:"

[github-actions[bot]]

clang-tidy review says "All clean, LGTM! :+1:"

[github-actions[bot]]

clang-tidy review says "All clean, LGTM! :+1:"

[github-actions[bot]]

clang-tidy review says "All clean, LGTM! :+1:"

[meyertst-aws]

I have looked over this code and tested it.