fix: aws function predefined role

[antoine-js]

Attempt in trying to fix the function's predefined role current issues for good.

With a solution like this one, we are now always having a iam.Role in a Function. No more issue with trying to access an undefined role from another component.

Instead of considering role to be undefined when predefined role is passed, we are now referencing the actual role. So the role will either be a reference or we create it if not passed.

Thats the idea but please let me know if I miss some important context on why it should not be done like this.

I have tried this solution with ApiGatewayV1 and NextJS server function. They now both work fine even though it didnt work in the past.

Closes sst/sst#4180

[antoine-js]

Hi @fwang, any chance you might have a look at this PR soon ? Sorry, it is a blocker currently in my company as APIGW V1 and predefined roles are mandatory, and we have a chance to run a POC for SST right now.

[jayair]

I'll check

[fwang]

There r some conflicts. Move the implementation here de2a081.

Will be in v3.1.73

Thanks @antoine-js