Fix camera permission

[emiliopavia]

Checklist

• [x] All new and existing tests pass
• [x] I've read the Contribution Guidelines
• [x] I've read Change Limitations

Motivation and Context

The app asks for camera permission after starting a recording for the first time. As it's not the right time to do that I made a refactor to fix it.

Description

The current implementation asks for camera permission just to know if the camera access is available. I split the two use cases in CameraAccessHandler:

static var hasGrantedAccess: Bool

returns the state without asking for the permission the first time.

static func checkForPermission(requestCompletion: ((Bool) -> Void)? = nil)

checks the permission state and request for it if it's .notDetermined. The result is handled via a callback that can be asynchronous.

Then I modified all the points in the app where these APIs were used.