Clarify that "component" is not used in a defined sense in Sensory Characteristics

[mbgower]

Addresses some of the points in #4252 by clarifying that the use of "component" is not mean as a synonym for the defined term User Interface Component in the normative wording of 1.3.3 Sensory Characteristics, which reads:

Instructions provided for understanding and operating content do not rely solely on sensory characteristics of components such as shape, color, size, visual location, orientation, or sound.