fix(core): Fn.select incorrectly short-circuits complex expressions

[rix0rrr]

In CloudFormation, it is possible to do the following:

'Fn::Select':
  - 0
  - - { 'Fn::If': ['Cond1', 'Value1', { Ref: 'AWS::NoValue' } }
    - { 'Fn::If': ['Cond2', 'Value2', { Ref: 'AWS::NoValue' } }
    - { 'Fn::If': ['Cond3', 'Value3', { Ref: 'AWS::NoValue' } }

Because the AWS::NoValues will disappear from the array, this
will evaluate to the first condition that is true.

CDK is unlikely to generate expressions like this, but people may have
written this in CloudFormation templates. The eager short-circuiting
behavior of Fn.select was breaking the roundtrippability of this
template's condition cascade through cloudformation-include, by
unconditionally picking out the first element from the array.

We can't get rid of the short-circuiting completely (as bunch of
templates and tests may already depend on it), but we can catch
this happening and guard against it, by not short-circuiting if
we can't look into all values.

---

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[gitpod-io]

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