Staging/libiio1 support

[dNechita]

PR Description

Update the library, the tests and the cmake such that libad9166 builds with libiio v1.x

PR Type

• Bug fix (a change that fixes an issue)
• New feature (a change that adds new functionality)
• Breaking change (a change that affects other repos or cause CIs to fail)

PR Checklist

• I have followed the coding standards and guidelines
• I have conducted a self-review of my own code changes
• I have commented new code, particulary complex or unclear areas
• I have built libad9166-iio and check no new warnings/errors were introduced
• I have checked that my changes did not broke components that use libad9361-iio as dependency
• I have updated the documentation accordingly (GitHub Pages, READMEs, etc)