[CMT] Modify name of Wizard Step two

Attachemnet1-1. Modify Name of 'OnLine DB' and 'OffLine DB'.
ex> [OnLine] --> [Online Migration]
[Load DB file] --> [Database Unload]

Attachemnet1-2. Add DBname to default filename of Wizard Step two.
ex> schema --> dbname_schema
index --> dbname_index
data --> dbname_data

Attachemnet1-3. [file name] of preview has to change "schema.txt" to "index.txt"