Secret Detection: Add Scanner Internals and Rename Terminologies

Why is this change being made?

MR Changes

• Rename references:
  • Scan Engine -> Scanner
  • "underlying scan engine" -> Scan Engine
  • Unified SD Scan Engine -> Unified SD Scanner
• Introduces Analyzer terminology to represent implementation wrapper for each scan target type.
• With the introduction of Analyzer term, Adapter becomes redundant as it would be a subset of Analyzer implementation. So, I've removed the concept of Adapters.
• Added a dedicated Components section containing terminologies used in Unified SD Scanner context. We could later move this to
• Adds Scanner Internals section under Secret Detection Unified Scan Engine ADR to describe the accommodation of multiple engines and interceptors.
• Modifies the illustration of high-level design for the Unified Scan Engine to reflect better description of the concept.

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Commits

• Add Scan Engine Component Internals

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