Feature request: Support renaming tables/columns in declarative workflow

[yoni-yad2]

In order to not lose data in declarative mode, please support an attribute/directive for tables/columns called rename_as, so Atlas will rename table/column name x as y, instead of dropping/recreating it with a new name.

During planning, Atlas should also pre-check that no two tables have the same name/rename_as value in the same schema or same column name/rename_as value in the same table.

Example:

table "remarks_table" {
  schema = schema.myschema
  rename_as = "comments_table"
  column "ID" {
    null           = false
    type           = int
    unsigned       = true
    auto_increment = true
  }
  column "remarks" {
    rename_as = "comments"
    null = true
    type = varchar(250)
  }
  primary_key {
    columns = [column.ID]
  }
}