refactor(robot-server): Use last run command for /runs/:runId/currentState links

[mjhuff]

Overview

In #16417, it was noted that links should include a reference to the last completed command as opposed to the "current" command in order to prevent torn state. This PR updates the link to do just that.

Test Plan and Hands on Testing

• Ran some protocols, noted that the command was in fact the last command at the time of query.

Changelog

• Updated the links property within the runs/runId/currentState response.

Review requests

c8dce60 - Updates the behavior for get_current_command for historical runs with the behavior that I think we want given the comment, but is this actually the case? CC: @SyntaxColoring

Risk assessment

low