refactor: make browserCheck an util instead of mixin

[ShGKme]

☑️ Resolves

• Fix Fix lost audio track on safari #11006 (comment)

• There is no need to be a mixin, it has nothing Vue-related or reactive
• Having this module as a mixin:
  • Limits the usage to only Vue components
  • Reruns checks and all version detections each time the mixin is used (though it is guaranteed that the browser cannot be changed in runtime)
  • Adds many unneeded properties to component instance listed in devtools

🖌️ UI Checklist

🖼️ Screenshots / Screencasts

No visual changes

🚧 Tasks

• Move the module browserCheck to utils
• Refactor computed and Vue component methods to exported constants and functions
• Update the usage in components
• Move callButtonTooltipText to CallButton as it was supposed to be used only in CallButton

🏁 Checklist

• 🌏 Tested with Chrome, Firefox and Safari or should not be risky to browser differences
• 🖌️ Design was reviewed, approved or inspired by the design team, or there is no visual change
• ⛑️ Tests are included or not possible
• 📗 User documentation in https://github.com/nextcloud/documentation/tree/master/user_manual/talk has been updated or is not required

[Antreesy]

Flawless. Tested in Chrome + Firefox

One non-blocking comment:

[SystemKeeper]

Awesome! Also tested with "real safari" works as well :)

[SystemKeeper]

/backport to stable28

[ShGKme]

Awesome! Also tested with "real safari" works as well :)

As I understood the problem, it was not reproducible in Safari on Mac. Only on specific old versions on iPad.

[SystemKeeper]

/backport to stable27