JS: Expose button event type in gui/widget button callback

[WillyJL]

What's new

• js gui/widget "button" element callback receives a ButtonEvent struct instead of just the button key
• allows user scripts to choose which event types to handle, otherwise a script based all around widget will struggle differentiating between event types and receive 3+ events for each button press

Verification

• gui.js example Widget pressing right to go back works as expected

Checklist (For Reviewer)

• PR has description of feature/bug or link to Confluence/Jira task
• Description contains actions to verify feature/bugfix
• I've built this code, uploaded it to the device and verified feature/bugfix

[portasynthinca3]

I've bumped the major version of the SDK since this is a breaking change. All extra features from SDK versions 0.1 through 0.3 are thus now recognized as baseline.