Fix permissions generation for Lambda ARNs with aliases

[NoxHarmonium]

We using ARN strings to specify Lambdas in step function tasks in one of our projects.
We can't use references like Ref: for various reasons and we build the ARN with string interpolation.

This worked fine up until we started using aliases and we started getting permission errors. It seems like the alias wildcard that was put into generate step function IAM role was appended to the ARN rather than replacing the specified alias.

This change strips off the alias if it already exists so the permission generation works correctly.

Previously this step definition:

SomeStep:
  Type: "Task"
  Resource: "arn:aws:lambda:${self:provider.region}:${self:provider.awsAccountId}:function:some-function:some-alias"
  End: true

Would create a step function role policy with a resource like:

{
    "Fn::Sub": [
    "${functionArn}:*",
    {
        "functionArn": "arn:aws:lambda:ap-southeast-2:12345678:function:some-function:some-alias"
    }
    ]
},

Which is invalid since the :* wild card is appended to the alias instead of replacing it.
It should actually look like this:

{
    "Fn::Sub": [
    "${functionArn}:*",
    {
        "functionArn": "arn:aws:lambda:ap-southeast-2:12345678:function:some-function"
    }
    ]
},

Let me know if this makes sense and I'm on the right track.

Thanks!

[theburningmonk]

LGTM

[theburningmonk]

🎉 This PR is included in version 2.6.1 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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