fix(event-handler): fix decorated scope in appsync events

[dreamorosi]

Summary

Changes

Please provide a summary of what's being changed

This PR improves the decorator logic of the AppSyncEventsResolver by fixing a fundamental issue that prevented it from being useful.

Prior to this fix the decorators would consistently cause the decorated methods to become unbound and lose the reference to this, preventing customers to access other class methods or properties from within the decorated methods.

This was happening because unlike other decorator implementations in the codebase, the one in this area of the codebase works in two steps:

1. at init time the decorator saves a reference of the decorated method for later usage
2. at runtime the app.resolve method can call a decorated method depending on routing decisions

By the time the reference is called, the initial scope is lost causing the issue. At the same time, the this scope is not yet available at init time - this is because decorators are evaluated before class init - so it's not possible to save a reference or bind this along with the the decorated method.

Because of this, we need to get around this decorator design aspect.

Specifically, at runtime (step 2) - which is when app.resolve() is called - we introspect the class methods, find their definition, and when we encounter the .resolve keyword (which represents the method), we save a reference to this for later use. This reference is then used and passed to the decorated method to apply the correct this value.

While this is relatively unorthodox, as long as we find one instance of this that belongs to the class to which the decorated method belongs it should be fine.

Please add the issue number below, if no issue is present the PR might get blocked and not be reviewed

Issue number: fixes #3973

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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