feat: migrator support table comment

[maiqingqiang]

• Do only one thing
• Non breaking API changes
• Tested

What did this pull request do?

migrator support table comment.

1. feat: migrator support table comment #6225
2. feat: migrator support table comment mysql#114
3. feat: support table comment gen#822

User Case Description

[jinzhu]

Maybe better to have an API like ColumnTypes to return table-related information...

[maiqingqiang]

Maybe better to have an API like ColumnTypes to return table-related information...

Okay, I'll make some changes.

[jinzhu]

Maybe better to have an API like ColumnTypes to return table-related information...

Okay, I'll make some changes.

Thank you, we can add a Tables method to the Migrator interface, it returns a TableType interface which contains Name, Comment... methods

[maiqingqiang]

Maybe better to have an API like ColumnTypes to return table-related information...

Okay, I'll make some changes.

Thank you, we can add a Tables method to the Migrator interface, it returns a TableType interface which contains Name, Comment... methods

Yeah, I think so too.

[maiqingqiang]

I've finished developing the TableType method. @jinzhu

        tableType := g.db.Migrator().TableType(tableName)
	log.Printf("table catalog: %s", tableType.Catalog())
	log.Printf("table schema: %s", tableType.Schema())
	log.Printf("table name: %s", tableType.Name())
	log.Printf("table type: %s", tableType.Type())

	engine, ok := tableType.Engine()
	log.Printf("table engine: %s ok:%v", engine, ok)

	comment, ok = tableType.Comment()
	log.Printf("table comment: %s ok:%v", comment, ok)

	log.Printf("tableType: %+v", tableType)

[yiranzai]

LGTM