Pre-fill database migration description

If you change (create or modify) just one table, pre-fill the database migration description, such as:

create_table_xyz
alter_table_xyz_add_column_email (when you add a single column)
alter_table_xyz_add_columns (when you add multiple columns)
alter_table_xyz (when you have additions and removals) 

Internally, Wappler could create a few variables:

let changedColumns = []
let changedTables = []

Create a new table:
changedTables.push("xyz")

Erase a table:
changedTables.push("-xyz")

Add a new column:
changedColumns.push("email")

Remove a new column:
changedColumns.push("-email")

These variables could be checked to generate the pre-fill description for the database migration