Deprecate renaming tables via TableDiff

[morozov]

Schema comparators do not detect renamed tables, so they do not populate TableDiff::$newName. Schema managers doing so in their renameTable() methods is a hack.

For comparison, ColumnDiff does not represent a change in the column name, it is tracked at a higher level, in TableDiff. By the same token, TableDiff should not represent a change in the table name. If it will be ever supported, it should be tracked in SchemaDiff.

Getting rid of handling the new name in the table diff is a prerequisite for future refactoring of the TableDiff API. Eventually, I want to get rid of public properties there and make the object immutable similar to what was done in ColumnDiff (#5657).

[greg0ire]

I think it's fine to have linebreaks inside this string and that this looks a job for nowdoc + sprintf.

Suggested change

	"DECLARE @sql NVARCHAR(MAX) = N''; "
	. "SELECT @sql += N'EXEC sp_rename N''' + dc.name + ''', N''' "
	. "+ REPLACE(dc.name, '" . $this->generateIdentifierName($oldName)
	. "', "
	. "'" . $this->generateIdentifierName($newName) . "') + ''', ''OBJECT'';' "
	. 'FROM sys.default_constraints dc '
	. 'JOIN sys.tables tbl ON dc.parent_object_id = tbl.object_id '
	. 'WHERE tbl.name = ' . $this->quoteStringLiteral($newName) . ';'
	. 'EXEC sp_executesql @sql',
	sprintf(
	<<<'SQL'
	DECLARE @sql NVARCHAR(MAX) = N'';
	SELECT @sql += N'EXEC sp_rename N''' + dc.name + ''', N'''
	+ REPLACE(dc.name, '%s', '%s') + ''', ''OBJECT'';'
	FROM sys.default_constraints dc
	JOIN sys.tables tbl ON dc.parent_object_id = tbl.object_id
	WHERE tbl.name = %s;
	EXEC sp_executesql @sql'
	SQL,
	$this->generateIdentifierName($oldName),
	$this->generateIdentifierName($newName),
	$this->quoteStringLiteral($newName)
	)

[morozov]

It was a copy-paste from getAlterTableSQL() which actually didn't need to be duplicated. I removed the original code and made the logic of the new method reused.