[FEATURE] Submit data for training backend

A lender should be able to submit a huge dataset for model development.
the data should be submitted with the following columns and in csv format.

1. transactional_data
```
a. transaction_id
b. unique_borrower_id
c. date_of_transaction
d. details_of_transaction
e. transaction_status
f. amount_transacted
```
2. loan_data
```
a. unique_loan_id
b. unique_borrower_id
c. loan_amount
d. repayment_period
f. interest
g. date_disbursed
h. date_repaid
```
3.customer_data
```
a. borrower_id
b. borrower_date_of_birth
c. borrower_gender
e. default_status

```
The json should be a dictionary of column names as keys and rows as a list of values. For example,
customer data should be converted to
```
{
"borrower_id": [1, 2, 3, 4, 5],
"borrower_date_of_birth": ['2011-05-03', '2011-05-03', '2011-05-03', '2011-05-03', '2011-05-03'],
"borrower_gender": ["male", "male", "female", "male", "female"],
"default_status": [0, 0, 0, 1, 0, 0]
}

```
A developer should create endpoints that will allow a lender to submit huge data for training. One endpoint will be for submitting transactional data and another endpoint should be for submitting loan data.