Basic coding convention - db initialization

[mirmahathir1]

Currently you have initialized all db connections in the index file like the following:

badhan-datainput-api/index.js

Lines 12 to 25 in 5c68202

	initializeApp({
	credential: cert({
	type: process.env.TYPE,
	project_id: process.env.PROJECT_ID,
	private_key_id: process.env.PRIVATE_KEY_ID,
	private_key: process.env.PRIVATE_KEY,
	client_email: process.env.CLIENT_EMAIL,
	client_id: process.env.CLIENT_ID,
	auth_uri: process.env.AUTH_URI,
	token_uri: process.env.TOKEN_URI,
	auth_provider_x509_cert_url: process.env.AUTH_PROVIDER,
	client_x509_cert_url: process.env.CLIENT_CERT_URL,
	}),
	});

Initialize your db connections in a seperate folder like the following:
https://github.com/Badhan-BUET-Zone/badhan-backend/blob/3983fe2d84a362ba3b63731967495cf485fd6d23/src/app.js#L15
https://github.com/Badhan-BUET-Zone/badhan-backend/blob/master/src/db/mongoose.js