Add convenience functions/classes for working with property values (eg URLs)

[feltech]

What

Alongside the generated trait views, add common convenience functions:

• filePathFromUrl / filePathToUrl - to ensure a consistent URL encoding scheme for file system paths (e.g. considering UNC paths, where there is no consensus).
• ...?

[foundrytom]

There is non-trivial work to add static code to these packages and single-source it. So it might be prudent to consider whether any of these could be justified in living in OpenAssetIO itself.

[elliotcmorris]

There methods are in core now, they're great.