When analytics are enabled, undefined file is created at the location where a command is executed. This is because the $options.analyticsLoggingFile is undefined, but we've set it as args to the spawned Analytics process. The value in the child process is the string "undefined", so that's why CLI always creates this file.
Pass the path to file only when it is passed by user.

PR Checklist

• The PR title follows our guidelines: https://github.com/NativeScript/NativeScript/blob/master/CONTRIBUTING.md#commit-messages.
• There is an issue for the bug/feature this PR is for. To avoid wasting your time, it's best to open a suggestion issue first and wait for approval before working on it.
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• Tests for the changes are included.

What is the current behavior?

When analytics are enabled, CLI always produces file called undefined, in which it saves the information what has been tracked.

What is the new behavior?

When analytics are enabled, CLI will produce file with name specified by user with --analyticsLogFile <name>, in which it saves the information what has been tracked.

Part of the implementation of: #4152