Implement QueryProvider for converting from IQueryable to Json string

[piotrczyz]

We already have a json parser for Directus format and we need an implementation of a QueryProvider that will be used for conversion from IQueryable to a query string.

Check the implementation of a QueryProvider here:
https://github.com/bcc-code/bcc-core-api/tree/main/sdk/dotnet/src

We want to copy that part into this repository and make it available for all projects using rule-filter-parser-dotnet nuget package.