Rename Shell class init method

[jballoffet]

🎉 New feature

Related: #87

Summary

This PR modifies the Shell class init method to begin from init, for consistency.

Test it

Tested by running the following commands and ensuring code builds and tests build and pass:

pio run

and

pio test --environment=desktop

Checklist

• Signed all commits for DCO
• Added tests
• Added example and/or tutorial
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if it affects the public API)

Note to maintainers: Remember to use Squash-Merge and edit the commit message to match the pull request summary while retaining Signed-off-by messages.

[jballoffet]

Thanks @francocipollone!