SetExistingRowsTo logic with system-versioned tables

[jzabroski]

Describe the bug
If you use advanced database features, SetExistingRowsTo will only set values on the main table, not the history table.

Create.Table("Example")
                .InSchema("dbo")
                .WithColumn("ExampleId").AsInt64().NotNullable().PrimaryKey()
                .WithColumn("Version").AsRowVersion().NotNullable();
                .WithColumn("ValidFromInUTC").AsDateTime2()
                    .WithDefault(SystemMethods.CurrentUTCDateTime)
                .WithColumn("ValidToInUTC").AsDateTime2()
                    .WithDefaultValue("CONVERT(DATETIME2(7), '9999-12-31 23:59:59.9999999')");

// ExampleHistory is a near verbatim copy of Example, except for keys.
Create.Table("ExampleHistory")
                .InSchema("dbo")
                .WithColumn("ExampleId").AsInt64().NotNullable()
                .WithColumn("Version").AsRowVersion().NotNullable();
                .WithColumn("ValidFromInUTC").AsDateTime2()
                    .WithDefault(SystemMethods.CurrentUTCDateTime)
                .WithColumn("ValidToInUTC").AsDateTime2()
                    .WithDefaultValue("CONVERT(DATETIME2(7), '9999-12-31 23:59:59.9999999')");

var schema = "dbo";
var table = "Example";
var historySchema = "dbo";
var historyTable = table + "History";
var rowStartDateColumn = "ValidFromInUtc";
var rowEndDateColumn = "ValidToInUtc";
Execute.Sql("ALTER TABLE [" + schema + "].[" + table + "] ADD PERIOD FOR SYSTEM_TIME([" + rowStartDateColumn + "], [" + rowEndDateColumn + "]);");
Execute.Sql("ALTER TABLE [" + schema + "].[" + table + "] SET(SYSTEM_VERSIONING = ON(HISTORY_TABLE = [" + historySchema + "].[" + historyTable + "], DATA_CONSISTENCY_CHECK = ON))");

// Due to semantics of how T-SQL works, any changes to dbo.Example table will flow through to dbo.ExampleHistory
Alter.Table("Example")
                .InSchema("dbo")
                .AddColumn("IsEnabled").AsBoolean().Nullable().SetExistingRowsTo(false);

// This will fail with an error
Alter.Column("IsEnabled")
                .OnTable("Example")
                .InSchema("dbo")
                .AsBoolean().NotNullable();

To Reproduce
Observe the following error:

ALTER TABLE [dbo].[Example] ALTER COLUMN [IsEnabled] BIT NOT NULL
The error was Cannot insert the value NULL into column 'IsEnabled', table 'FluentMigratorTests_John.Zabroski.dbo.ExampleHistory'; column does not allow nulls. UPDATE fails.
The statement has been terminated.

Expected behavior
Should be in-line with Microsoft documented behavior in article Changing the Schema of a System-Versioned Temporal Table (or, at minimum, the Remarks visible in IntelliSense of FluentMigrator should call out this gotcha):

If you add a non-nullable column or alter existing column to become non-nullable, you must specify the default value for existing rows. The system will generate an additional default with the same value and apply it to the history table. Adding DEFAULT to a non-empty table is a size of data operation on all editions other than SQL Server Enterprise Edition (on which it is a metadata operation).

We can also look at what Postgres does.

Information (please complete the following information):
FluentMigrator 3.3.1

Additional context
Add any other context about the problem here.