feat: pass parsed features to setWindowOpenHandler() callback

[miniak]

Description of Change

We already have the parsing code in Electron, dealing with the raw features string in the app code is inconvenient.

Checklist

• [x] PR description included and stakeholders cc'd
• [x] npm test passes
• [x] tests are changed or added
• [x] relevant documentation is changed or added
• [x] PR release notes describe the change in a way relevant to app developers, and are capitalized, punctuated, and past tense.

Release Notes

Notes: Passing parsed features as details.parsedFeatures to setWindowOpenHandler() callback.

[nornagon]

Marked as wip pending response from @miniak