Add table only export (/import) to File menu entries

[sbl]

db.out.ogr only allows export of tables connected to vector layers, while db.copy (in principle) can copy any table between different DB formats.

It would thus make sense to add db.copy to the menu under: "File" -> "Export database table" and probably even replace db.out.ogr in the long run there.

Same applies for import (db.in.ogr vs. db.copy).

No idea if db.in|out.ogr has better performance than db.copy. If that is the case a new module could be written as a wrapper around those two...