Use non-deprecated openassetioPlugin plugin system hook #127
Description
What
Switch from the deprecated plugin hook to the non-deprecated openassetioPlugin hook as the entry point for OpenAssetIO plugin system scanning.
Why
Now that we state in the release notes "Minimum OpenAssetIO version increased to v1.0.0-beta.2.2" we can safely remove support for the deprecated hook, and avoid the deprecation warning that using it generates.