Add IRepository.GetAsync and IRepository.FindAsync methods those get predicate

[hikalkan]

This simplifies to query a single entity that has a complex primary key.

Signatures:

/// <summary>
/// Get a single entity by the given <paramref name="predicate"/>.
/// It returns null if no entity with the given <paramref name="predicate"/>.
/// It throws <see cref="InvalidOperationException"/> if there are multiple entities with the given <paramref name="predicate"/>.
/// </summary>
/// <param name="predicate">A condition to find the entity</param>
/// <param name="includeDetails">Set true to include all children of this entity</param>
/// <param name="cancellationToken">A <see cref="T:System.Threading.CancellationToken" /> to observe while waiting for the task to complete.</param>
Task<TEntity> FindAsync(
    [NotNull] Expression<Func<TEntity, bool>> predicate,
    bool includeDetails = true,
    CancellationToken cancellationToken = default
);

/// <summary>
/// Get a single entity by the given <paramref name="predicate"/>.
/// It throws <see cref="EntityNotFoundException"/> if there is no entity with the given <paramref name="predicate"/>.
/// It throws <see cref="InvalidOperationException"/> if there are multiple entities with the given <paramref name="predicate"/>.
/// </summary>
/// <param name="predicate">A condition to filter entities</param>
/// <param name="includeDetails">Set true to include all children of this entity</param>
/// <param name="cancellationToken">A <see cref="T:System.Threading.CancellationToken" /> to observe while waiting for the task to complete.</param>
Task<TEntity> GetAsync(
    [NotNull] Expression<Func<TEntity, bool>> predicate,
    bool includeDetails = true,
    CancellationToken cancellationToken = default
);