Make instances of most type classes local

This follows a discussion there #91 (comment 79359)

If we choose to go this way, we should probably do the same for the other ProcessorState instances (spin and varspeed) as well as for instances of JobReady and JobPreemptable and a few other things.

analysis/abstract/definitions.v

 From mathcomp Require Import ssreflect ssrbool eqtype ssrnat seq path fintype bigop.
 Require Export prosa.model.task.concept.
 
-(** Throughout this file, we assume ideal uni-processor schedules. *)
-Require Import prosa.model.processor.ideal.  
-
 (** * Definitions for Abstract Response-Time Analysis *)
 (** In this module, we propose a set of definitions for the general framework for response-time analysis (RTA) 
     of uni-processor scheduling of real-time tasks with arbitrary arrival models. *)