fix: compilation errors with functional_tests flag

[geekbrother]

Description

When the --features functional_tests flag is enabled there are few errors that break the building process:

error[E0308]: mismatched types
  --> tests/functional/singletenant/push.rs:62:16
   |
62 |         topic: Some(topic.into()),
   |                ^^^^^^^^^^^^^^^^^^ expected `String`, found `Option<_>`
   |
   = note: expected struct `std::string::String`
                found enum `Option<_>`

error[E0308]: mismatched types
  --> tests/functional/stores/notification.rs:38:20
   |
38 |             topic: None,
   |                    ^^^^ expected `String`, found `Option<_>`
   |
   = note: expected struct `std::string::String`
                found enum `Option<_>`

Seems that functional tests are out of sync with recent changes. To fix that I've changed fields to the expected types in the errors to make them in sync with the recent changes and make the functional tests compile.

Resolves #194

How Has This Been Tested?

It was tested by running cargo test --features functional_tests.
The expected result is successful test building with the functional_tests enabled without errors.

Due Diligence

• Breaking change
• Requires a documentation update
• Requires a e2e/integration test update

[xav]

If the tests are working again, can we run them in the CI too?
I don't know why we ever stopped actually.

[chris13524]

LGTM.

And yeah, would be great to run these in CI/CD!

[geekbrother]

If the tests are working again, can we run them in the CI too?

Not exactly, they compile, but some of them fail (I assume they are out of sync with changes). These PR changes make the functional tests compile and #196 fixes the client_upsert test.

And yeah, would be great to run these in CI/CD!

Yeah, we can fix failing tests and fix a few low-hanging fruits to make it work in a CI/CD. I will create an issue for this, but not sure about the prioritization of this task cc @xav , @arein .

[geekbrother]

If the tests are working again, can we run them in the CI too?
And yeah, would be great to run these in CI/CD!

#198 enabling the functional testing in our CI workflow.