Allow sub queries in inserts alongside parameters

[patrickratzow]

Allow mixing parameterized insert queries & query inserts. This is very useful when you have some of the data, but is looking to get the rest of the data directly in the database without having to execute another query in C#, due to it increasing the overall time spent as a result of the extra round trip.

Example use case

var discordId = "discord_id_value";
var steamId = "steam_id_value";
var query = new Query("Discord")
    .AsInsert(
        new[] {"Id", "UserId"},
        new object[]
        {
            discordId,
            new Query("User")
                .Select("Id")
                .Where("SteamId", steamId)
        }
    );

Which would then compile into

INSERT INTO
  [Discord] ([Id], [UserId])
VALUES
  ('discord_id_value', (SELECT [Id] FROM [User] WHERE [SteamId] = 'steam_id_value'))