feat: add support for batch column add

[mahendraHegde]

What kind of change does this PR introduce?

support to add multiple column to a table

• change POST /columns to support both object and array of columns
• change columns.create method to accept array instead of plain object
• modify and add new test cases

What is the current behavior?

we need to add columns 1 by 1

What is the new behavior?

we will be able send columns as an array(batch) or object(backward compatibility) to the POST /columns endpoint closes #182

swagger updated

[mahendraHegde]

@soedirgo PR is ready, plz review