Allow `GoTrueClient` injectable to SupabaseClient initializer

[kurtguenther]

Feature request

It would be great a GoTrueClient to be injected as a parameter to SupabaseClient initializer.

Is your feature request related to a problem? Please describe.

We have a specific Keychain configuration that we need to inject to the GoTrueClient (whose initializers already support injecting their own KeychainStorage/GoTrueLocalStorage. Our app will not be able to use the defacto Keychain location that is being provided in the GoTrueClient(...) init that this initializer is using.

Describe the solution you'd like

This could be as easy as allowing a new constructor

  public init(
    supabaseURL: URL,
    supabaseKey: String,
    schema: String = "public",
    headers: [String: String] = [:],
    httpClient: HTTPClient = HTTPClient(),
    authClient: GoTrueClient
  ) {

It seems that the auth client does depend on the headers, so maybe allowing some kind of convenience method on GoTrueClient(...) to construct it based upon the existing supabaseURL and supabaseKey which are added via the defaultHeaders property, would be helpful.

Describe alternatives you've considered

Instead of being provided to the initializer, the auth property could become a var for an automatic get or there could be another function like setAuthClient(...) that is exposed. But that would probably introduce some weird conditions that are tougher to reason about rather than just injecting in the init(...)

Additional Context

If either approach is acceptable, I'm happy to write it up and put up a PR.
Thanks.

[maail]

@GRSouza thoughts? You would have more context.

[grdsdev]

I understand the need for this, I would just check if the official JS library already has a way of solving this, and try to implement the same behavior, otherwise the one suggested is good and I can add it.

[grdsdev]

Hi @kurtguenther check out #72

I decided to follow the same approach supabase-js uses, you can pass a custom implementation of the GoTrueLocalStorage protocol when initializing the SupabaseClient now.