fixed inference disruption problem

[sam4coding]

Originally, the default value of "isInference" is 'false'. Whenever the component is rendered, the value of "isInference" is automatically set to false. So it appeared that when we switch out from and then back to "inference" tab, the "start inference" button is activated, as if the inference stopped.
In this update, the variable pair { isInference, setIsInference} is replaced by a new pair { isInferring, setIsInferring }. And they became the prop of the component . The value of "isInferring" is updated solely by "setIsInferring", not by any initializing default value. By this, the status of the "start inference" button is solely determined by the status of inferring.

[mansouralawi]

Thanks for the PR, issue fixed.