Add Dereference template function

[RedbackThomson]

Description of changes:
This PR adds a Go template function for de-referencing strings. Go templates do not, out of the box, support string de-referencing when doing string comparison. When comparing a string pointer to a pointer it gives a fatal type mismatch error.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[vijtrip2]

/lgtm

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[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: RedbackThomson, vijtrip2

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[jaypipes]

Did we have an example where this was occurring? Or a GH issue that described the problem?

[RedbackThomson]

Did we have an example where this was occurring? Or a GH issue that described the problem?

Sorry, I did not create a feature request to attach. The only description is the body of this PR. It's for changes to the S3 hook templates.

[jaypipes]

Did we have an example where this was occurring? Or a GH issue that described the problem?

Sorry, I did not create a feature request to attach. The only description is the body of this PR. It's for changes to the S3 hook templates.

No need to apologize, @RedbackThomson, I was just curious where we were running into the fatal type mismatch thingie... :)