Please provide a way to execute code before AzureFunctionInstanceInjector create the context

[mbaxr]

Is your feature request related to a problem? Please describe.
I want have a way to execute code for running checks/configurations before the AzureFunctionInstanceInjector start the application and Logback

Describe the solution you'd like

1. Define an Injectable optional class/es that get executed before Spring context initialization
2. Don't use Logback logging in spring-cloud-function-adapter-azure classes, this could cause Logback to be executed before the above section class code

Describe alternatives you've considered
Only alternative is to rewrite the AzureFunctionInstanceInjector and remove the package from dependencies because AzureFunction don't support multiple instance injector