Move examples to a central directory

[calavera]

Signed-off-by: David Calavera [email protected]

Description of changes:

• Move all the examples that are separated across several directories to a central place, so they are easy to find.
• Separate each example into its own Rust project, so they also include all their dependencies, and they are easier to copy/paste.
• Add a build step to check the examples in CI to verify that they always work.
• Add more information to several READMEs.

By submitting this pull request

• I confirm that my contribution is made under the terms of the Apache 2.0 license.
• I confirm that I've made a best effort attempt to update all relevant documentation.

[bnusunny]

LGTM