Refactor Matrix API errors handling

[PenguinBoi12]

matrix-nio's AsyncClient returns ErrorResponse instead of raising when an request error happens. Our current try/except pattern only caught lower level exception exceptions, so a rejected call either silently succeeded or raises a confusing AttributeError message instead of the real server error. To fix the issue and handle errors correctly, a wrapper called matrix_call() was added to wrap every AsyncClient calls and translates all type of error into a MatrixError with the actual API error message.

Additionally to adding the wrapper, all places making calls using the old pattern were refactored to use matrix_call instead.

Example

response = await matrix_call( 
    self.client.room_kick(
        room_id=self.room_id,
        user_id=user_id
    ), 
    error_message="Failed to kick user", 
)

[chrisdedman]

Thank you. Great pattern for better errors handling. LGTM