Support downloading of form submissions containing repeat group in csv format

[susmina94]

Current Situation Currently, our system allows users to create forms with repeat groups to collect structured and repeatable data. However, when users attempt to download these form submissions, the system only supports downloading the data in non-relational formats (e.g., JSON or XML). While these formats are useful for various purposes, there is a growing demand for CSV downloads as it is a widely accepted and easily readable format, especially for data analysis and reporting purposes.

Proposed Solution This feature request is to enhance our system's capabilities by adding the option to download form submissions containing repeat groups in CSV format. This would empower our users to seamlessly export their data in a tabular, structured, and easily analyzable format, streamlining their data processing workflows.

Expected Behavior The expected behavior of this feature request can be summarized as follows:

1. Users should have the option to select the format in which they wish to download form submissions (e.g., CSV, JSON, XML) with CSV being the new addition.
2. The CSV download should accurately represent the hierarchical structure of the form, including repeat groups.
3. All relevant data from form submissions, including metadata and repeatable group data, should be included in the CSV file.
4. Users should have the ability to specify the structure of the CSV file, such as defining the delimiter, column headers, and data formatting options.