Send SMS API

[Rustix69]

Fixes : Issue #10

Implementation :

1. Gets patient details: Extracts the patient ID and ABHA address from the validated data.
2. Retrieves the patient's phone number: Queries the database to get the patient record using the external_id field, which allows us to access the patient's phone number.
3. Generates a random 6-digit OTP: Creates a secure random OTP instead of the hardcoded "000000".
4. Sends an SMS to the patient: If the patient record is found and has a phone number, it sends an SMS with the OTP and ABHA address using the existing send_sms function from the care core.
5. Stores the OTP in the cache: Updates the cache with the generated OTP and other necessary information.

The SMS message includes :

• The OTP
• The ABHA address being linked
• A note about the OTP's validity period (10 minutes)

[khavinshankar]

Needs changes,

• Use the abdm_emr branch as the base instead of main
• Use emr.Patient instead of facility.PatientRegistration
• Remove the comments unless you want to highlight something that is not a standard practice.

[khavinshankar]

@Rustix69 The logic looks good to me but some changes are required which I have highlighted above