Balena removal: opentrons integration: Execute integration

[sfoster1]

Per #2876 integrate the buildroot and opentrons repos:

1. As an Opentrons API developer, I want to be able to do my work without ever thinking about buildroot, with as little change from the current state of affairs as possible
2. As an Opentrons system developer, I want to be able to easily coordinate changes in the API server and buildroot layers
3. As an Opentrons devops/infrastructure person, I want to always have buildroot builds available for canonically "latest" builds

These lead to this implementation strategy:

The opentrons api (and possibly the update server / some new embodiment of the update server) are added to buildroot as python packages, built from source.

The version of the api used is determined by the following rules:

• If there exists a branch of https://github.com/opentrons/opentrons that matches the current branch name, that version is used
• Otherwise, edge is used

On the CI side, we have the following triggers:

On push and pr open to https://github.com/opentrons/buildroot:

• Build buildroot using the above rules

On push and pr open to https://github.com/opentrons/opentrons:

• If the branch matches a branch in buildroot start a buildroot build of the matching branch (using above logic, but without the default to edge)
• If the branch is edge [optional: and the diff since last build contains changes to api/, shared-data/, update-server/], build opentrons-develop of buildroot
• If neither of those rules match, do not build buildroot

Change make push-api to:

• remount the rootfs rw
• transfer the wheel
• pip install the wheel
• reboot the system

(the push-api part should probably be a different target so as not to interfere with current workflows)