feat(robot_context): Add pipette helper functions to convert volume and position type

[Laura-Danielle]

Overview

For the robot_context, it is important to be able to convert volume and named positions to an AxisMap so that it can be passed in to the robot_context move functions.

Test Plan and Hands on Testing

Tested on a flex to verify that the pipette moves to the correct locations.

Changelog

• Expose plunger position and aspirate/dispense commands.
• add the pipette conversion functions
• expose plunger positions in the pipette dict

Review requests

Are we OK with some of the conversions living in the robot core?

Risk assessment

Low, unreleased API.

[sfoster1]

I see what we're getting at, but I think we should do it a little differently. Specifically,

• We should not do this in the core. Doing this in the core makes it impossible to execute commands of this type outside python protocols; it also pushes logic, or in this case duplicates logic, pretty high up. Instead, what about making the engine commands that you would give the positions to take either volume or distance, and convert internally? And for the conversions, let's make the actual math and the actual detail lookup part of an engine state handler that the api drills into, so that the logic and the lookup doesn't live in the core files.
• let's not duplicate things like ul per mm. They're data agnostic so let's make them shared utility functions.
• if we're going to push stuff into the engine, let's push it all the way. we definitely should not have new things in core/engine that reach into the hardware controller directly - let's get that stuff from the engine.