Feat: DSC API Request with User-Agent

Description of changes

Before

To call DSC API you had to be registered in their whitelisted Pp addresses list When trying to call the DSC API from a non-whitelisted ip addresses, you would get:

Picture 1 error_not_whitelisted

After

To remove the need for DSC to whitelist every IP addresses, we will use a User-Agent provided in the request header to identify and get the authorization. When trying to call the DSC API from a non-whitelisted ip addresses, you wil get:

Picture2

How ?

Create an environment variable for the User-Agent
Add its value to the config
Pass it as a header for every call to DSC in DscProvider.

Notes

Maybe we could extract the headers in an object since they are the same for all the request, to avoid duplication ?

Tests

On local env :

[x] Test on a non-whitelisted address IP, without the User-Agent header (see picture 1)
[x] Test on a non-whitelisted with the User-Agent header (see picture 2)
[x] Test on a non-whitelister with the User-Agent header and a bad naming :

error_bad_name (The retrieved error message is the correct one)

Badsender-com / LePatron.email