Support RuntimeContext and provide access to FilterExpressionCompiler from CustomFilters

[statler]

• Added RuntimeResolutionContext to allow passing in variables which will be accessibl in the CustomFilterCompiler execution
• Added additional property to the DataSourceLoadOptions for RuntimeResolutionContext
• In CustomFilterCompilers add new CompilerFuncsWithContext to support RuntimeResolutionContext without changing signatures for existing users
• Make FilterExpressionCompiler public and add public method to support leveraging CompileBinary method. This allows complex operator resolution without duplicating the devex operations.

[statler]

Implementation of Automapper integration - for discussion