chore(devtool): build devtool artifact and commit to other branch

[quekyj]

Description & Motivation

To test out the unreleased version of the devtool_extension, we can allow github action to commit the build artifact and modified the .gitignore. So, user can point to this package in pubspec.yaml via the use of:

rohd:
     git:
       url: https://github.com/quekyj/rohd.git
       ref: artifacts

Branch that have the artifact:

• artifacts

Testing

Tested on fork.

Backwards-compatibility

Is this a breaking change that will not be backwards-compatible? If yes, how so?

no

Documentation

Does the change require any updates to documentation? If so, where? Are they included?

No.