Table name case problem

Description

After the change of #321 , a table named like UpperCaseName will cause error failed to add table to sqle context.

Reason

The DDL library save table name in lower case.

func (ctx *Context) UpdateContext(node ast.Node, dbtype string) {
	switch s := node.(type) {
	...
	case *ast.CreateTableStmt:
		schemaName := ctx.getSchemaName(s.Table)
		tableName := s.Table.Name.L // <--- HERE
		if ctx.HasTable(schemaName, tableName) {
			return
		}
		ctx.AddTable(schemaName, tableName,
	...

MySQL option lower_case_table_names

https://dev.mysql.com/doc/refman/8.0/en/identifier-case-sensitivity.html

Column, index, stored routine, event, and resource group names are not case-sensitive on any platform, nor are column aliases.

ca9b80e is considered a temp fix. It saves table context in a map by lower case name

tableMap[strings.ToLower(table.TableName)] = config.NewTableContext(...)

Generally the name should be saved in original case.

The nature of the problem: In skipRowEvent, table name is matched with lower case.

						if b.matchString(tableName, tableLower) {
							return false, tableCtx
						}