feat: support boolean literals removal for prefer-conditional-expressions auto-fix

[incendial]

What is the purpose of this pull request? (put an "X" next to an item)

• Documentation update
• Bug fix
• New rule
• Changes an existing rule
• Add autofixing to a rule
• Add a CLI option
• Add something to the core
• Other, please explain:

Second part of #1094 improving the existing rule to discard boolean literals.

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
No Duplication information

[github-actions]

Dart Code Metrics unused files report of dart_code_metrics. ✅

Summary

• Scanned package folders: bin, example, lib
• No unused files found! ✅

[github-actions]

Dart Code Metrics analyze report of dart_code_metrics. ✅

Summary

• Scanned folders: bin, example, lib, test

• Total scanned files: 535

• Total lines of source code: 9428

• Total classes: 404

• Average Cyclomatic Number per line of code: 0.37 / 2

• Average Source Lines of Code per method: 6

• Total tech debt: 1968.0 hours

• Found issues: 5 ⚠

[codecov]

Codecov Report

Merging #1096 (a9f4800) into master (e77069d) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1096      +/-   ##
==========================================
+ Coverage   85.07%   85.09%   +0.01%     
==========================================
  Files         339      339              
  Lines        7412     7418       +6     
==========================================
+ Hits         6306     6312       +6     
  Misses       1106     1106              

Impacted Files	Coverage Δ
...pressions/prefer_conditional_expressions_rule.dart	100.00% <100.00%> (ø)

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