Test: Add tests for Athentication and CORS for gRPC-Gateway

[themantre]

Tests should be added to the gRPC-Gateway package to ensure that authentication and CORS are working as intended.
This can be either an integration test or even a unit test.

Different scenarios to cover include:

• Without Basic Auth and No CORS

  1. No password should work.
  2. Using a password should fail.

• With Basic Auth and No CORS

  1. No password should fail.
  2. Valid password should work.
  3. Invalid password should fail.

• Without Basic Auth and CORS

  1. No password with invalid CORS should fail.
  2. No password with valid CORS should fail.

• With Basic Auth and CORS

  1. No password with valid CORS should fail.
  2. Valid password with valid CORS should work.
  3. Valid password with invalid CORS should fail.
  4. Invalid password with valid CORS should fail.