update mac support

[thomassth]

If I have to guess, most of the new files are auto generated?

What are the actual changes in this commit?

[thomassth]

Tried building it today with the example app While the UI opens, no calendar info was parsed

[lukemmtt]

Regarding the bug discussed here earlier (i.e. permissions not working right for macOS builds launched from VSCode or Android Studio), I've gathered some likely-relevant discussions for reference:

• device_calendar: "macOS support" #471 (Another macOS-related open PR where the same issue was encountered.)
• Flutter: Macos app doesn't run in sandbox when using flutter run (Closed, unresolved. Was opened by @gaetschwartz, good summary.)
• Flutter: MacOS Permission problem in VSCode (Open. Was opened by maintainer of reminders plugin.)
• Flutter: Fails to Load Info.plist in macOS with vscode and Android Studio (Open. Seems like a strong lead on what the root cause is here.)

For what it's worth, my workflow for debugging anything involving Calendar or Reminders macOS permissions right now is:

1. Launch debug or release build from Android Studio. Permissions will not work at this stage, and any attempt to read permission will return PermissionStatus at the OS level.
2. Ensure the launcher icon is saved in the dock, then close the app & reopen it by clicking on icon in dock
3. Permissions work as expected.