Obtain config from Azure App configuration

[EliuX]

Env variables were fair-enough for storing configuration variables in an initial stage of the project, in order to make the application work. But it has its limitations:

• Secrets are not secure and exposed as plain texts in environments and .env files
• You cannot change that configuration without redeploying the application: The variables are set when the image is built.
• There is no referential consistency: They must be set everywhere they are needed. When a change must be applied, we should remember where they were set before, and set them again.

Because of this and the sake of good practices we were proposed to use Azure App Configuration. This way we can store sensitive config values in a secrets vault and link them to an Azure App Configuration account that should be created for the project (I think one is enough for now). Also, regular configuration values like feature toggles can be stored there. This is safer, more comfortable due to the centralization and better organized.

TODO:
After an Azure App Configuration account is created and ready to use, we should be able to bring variables like the database connection URI from there. The app should be able to run and function properly just by setting the environment (production).

[EliuX]

At this moment, we do not need to store feature toggles nor other kinds of variables in App Configuration, so we are going to limit our efforts for now in just populating up the Key Vault with the credentials to connect to our Cosmos DB database. We will link these variables to the configurations in App Service and Azure DevOps where they are required. I tried to do so, but even after I got additional permissions, I am still unauthorized to do all that is required. Therefore, this task shall be done by our DevOps developer @fabidick22.