Refactor results.py

[DonggeLiu]

Unify and redesign all result classes:

1. Most result classes are in results.py but some others scattered in different files with duplicated names/attributes. For example, buildresult and runresult in builder_runner.py, SemanticCheckResult, and AggregatedResult. We should move them to one place for easier maintenance, merge some of them to avoid duplications, and redesign them for simpler accesses.
2. Many result classes in results.py are too complex due to inheritance. For example, RunResult has more than 20 attributes, many of them come from BuildResult and Base Result classes. We need to simplify their design. For example, having a result class with multiple subclasses for build/run/analysis status:

class Result:
  benchmark: Benchmark
  build: optional[BuildStatus] = None
  run: optional[RunStatus] = None
  analysis: optional[AnalysisStatus] = None
 ...

class BuildStatus:  # Or other names, same below.
  fuzz_target_source: str
  build_script_source: str
  compiles: bool
  ...

class RunStatus:
  crashes: bool
  ...

class AnalysisStatus:
   crash_analysis: CrashAnalysis
   coverage_analysis: CoverageAnalysis
   ...

class CrashAnalysis:
  vulnerability: bool
  ...

class CoverageAnalysis:
  needs_improvements: bool
  ...

[internot169]

@DonggeLiu - I'm interested in working on this! Could you please assign the issue to me?

[Ekam219]

@DonggeLiu - May i work on this?

[zewei-wang]

I already started the design and implementation. This issue is assigned to me. Sorry guys. @internot169 @Ekam219