build and deploy commands: --skip-static and --skip-actions flags should be mutually exclusive

It is possible for a user to specify both --skip-static and --skip-actions flags for the `build` and `deploy` commands.
It doesn't make sense to skip both (the CLI will report 'there is nothing to do').

Change the flags to be mutually exclusive. However, this will be a breaking change (since now specifying both flags will result in an error, when it was ok before).

Start at the command entry points for the `build` and `deploy` CLI commands and inspect how `--skip-static` and `--skip-actions` are defined and validated. Verify the behavior for each flag alone and for both together; done means the combined flags produce an error instead of reporting that there is nothing to do.

Written by the indexing model from the issue text.