FindWithChildren supporting expressions

[AlexanderS]

It would be really great if there were methods for finding a single object by a query and without primary-key. Just like the FindWithQueryAsync methods of SQLite-net.

Just like the following methods just as "WithChildren":

public Task<T> GetAsync<T> (Expression<Func<T, bool>> predicate)

public Task<T> FindAsync<T> (Expression<Func<T, bool>> predicate)

On top of that the following method would be great:

public Task<T> QueryWithChildrenAsync<T>(AsyncTableQuery<T> query);