Refactored into 2 functions (and 1 helper function for validating inputs)

[anchit-chandran]

Overview

• refactored the code into 2 functions UK_WHO_SDS_CENTILE and UK_WHO_DECIMAL_AGE, with flags to get appropriate data
• test_helper_ validates inputs, throws errors if any input incorrect

Functionality

1. User enters data into columns - GSheets should automatically convert dates to datetime columns. This is converted to strings and fed to the api
2. The specific flags for each function determine the output (specified by the data_to_return parameter). The default return will be all values.
3. User requires primary_api_key as one of the arguments
4. Appropriate error messages for invalid inputs

Pls check

1. Unsure how to make "professional" - don't know typescript
2. Function descriptions

[pacharanero]

Looks good to me. I will look into how we publish this to Google Sheets. https://developers.google.com/apps-script/add-ons/how-tos/publish-add-on-overview

[pacharanero]

Great work @anchit-chandran. Merged