BE 1 - Implement create_cohort API function

[LeandroHamaguchi]

Create an API function to add new Roles to the database. Here are some resources:

• Our Supabase dashboard's documentation on how to work with the Cohorts table
• Our Supabase Cohorts table schema.

Notes:

• The API functions should be written inside src/lib/api/
• Ensure proper error handling and validation of input data
• Include a description of the ticket and the implementation in the PR (with screenshots showing that it works!)

The goal is to:

• Create a function that accepts roles data and inserts it into the Supabase database
• Return appropriate success response and throw errors
• The return value should be the data object returned from the method .from("Cohorts").select()