Structure refactor

[thientc]

Refactor based on this flow for better understanding,

Library Source Code
        |
        v
  [FutagAnalyzer]  (Clang checker, runs via scan-build)
        |
        v
  JSON analysis files:
    .declaration-*.json  (function signatures)
    .context-*.json      (call contexts)
    .types-info-*.json   (enums, records, typedefs)
    .file-info-*.json    (includes, compiler options)
        |
        v
  futag-analysis-result.json  (aggregated by Python preprocessor.py)
        |
        +---> [Python Generator]  (generates fuzz targets)
        |
        v
  futag-4consumer.json  (subset for consumer analysis)
        |
        v
Consumer Source Code + futag-4consumer.json
        |
        v
  [FutagConsumerAnalyzer]  (Clang checker)
        |
        v
  _funcname_varname_blocks.json  (per-context files)
        |
        v
  futag-contexts.json  (aggregated by Python preprocessor.py)
        |
        v
  [Python ContextGenerator]  (generates context-based fuzz targets)