Add an --output-file option to DAML Script

[cocreature]

This PR adds an --output-file option to DAML Script that writes the
result of a DAML Script to a file and complements the --input-file option.

changelog_begin

• [DAML Script] daml script now has a `--output-fileoption that can be used to specify a file the result of the script should be written to. Similar to--input-file`` the result will be output in
  the DAML-LF JSON encoding.

changelog_end

Pull Request Checklist

• Read and understand the contribution guidelines
• Include appropriate tests
• Set a descriptive title and thorough description
• Add a reference to the issue this PR will solve, if appropriate
• Include changelog additions in one or more commit message bodies between the CHANGELOG_BEGIN and CHANGELOG_END tags
• Normal production system change, include purpose of change in description

NOTE: CI is not automatically run on non-members pull-requests for security
reasons. The reviewer will have to comment with /AzurePipelines run to
trigger the build.

[aherrmann-da]

The markup in the changelog message has a backtick missing before --output-file.

[aherrmann-da]

LGTM

[cocreature]

The markup in the changelog message has a backtick missing before --output-file.

At this point the changelog first goes to a google doc, then back to rst and then back to markdown. All hope of preserving markup is lost 😭