Changes to build and pass tests

[shepazon]

This pull request includes various smaller changes to let the examples build, run, and pass tests on the SDK as of today.

Among these changes, across all samples:

• Removed places where the error logging level is expressly set.
• Set the minimum swift-tools version to 5.9 to match the minimum supported by the SDK
• Added test.sh scripts to examples that don't have XCTest tests available; these simply print a message that no tests are available and return.

• A couple of small modernizations to a package file or two.

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