hcl2template: add alltrue & anytrue function

[mogrogan]

alltrue

Function that return true if all elements of the collection are true

manual tests

tested with packer console --config-type=hcl2

> alltrue([true, false])
false
> alltrue(["true", true])
true
> alltrue(["true", 123])
> Error: Invalid function argument

  on <console-input> line 1:
  (source code not available)

Invalid value for "list" parameter: element 1: bool required.

anytrue

Function that return true if at least 1 element is true

manual tests

tested with packer console --config-type=hcl2

> anytrue([true, false])
> true
>

> anytrue([true, true])
> true
>
>
> anytrue([false, false])
> false
>

> anytrue(["true"])
> true
> anytrue(["true", 123])
> Error: Invalid function argument

  on <console-input> line 1:
  (source code not available)

Invalid value for "list" parameter: element 1: bool required.

Closes #13073

[lbajolet-hashicorp]

Overall LGTM, I left a couple comments mostly about the copyright/license header, and left one question on the implementation of any_true, but besides those we're good to go.

Pre-approving this one

[lbajolet-hashicorp]

I wonder if we cannot declare the function as not accepting null/unknown? Though this might make sense to support them and return false immediately in that case so please feel free to push back on this comment.

[mogrogan]

I think that user of this function have good chance of being using terraform and I think we should keep consistency with the terraform project to reduce the risk of having confusing error.

[lbajolet-hashicorp]

I assume this behaviour was lifted from Terraform, but I find this somewhat debatable? Since the function is called AnyTrue, if one value is effectively true, I don't think we should care about one value being unknown in there

[mogrogan]

I agree with you, when I took that from terraform I found it a bit weird but I think the consistency between packer and terraform is more important unfortunately.