False-positive for `xct_specific_matcher ` rule with optional boolean

New Issue Checklist

• Updated SwiftLint to the latest version
• I searched for existing GitHub issues

Describe the bug

The xct_specific_matcher rule should not trigger when one of its arguments is an optional boolean.

Complete output when running SwiftLint, including the stack trace and command used

$ Pods/SwiftLint/swiftlint lint TestTests/TestTests.swift
Linting Swift files at paths TestTests/TestTests.swift
Linting 'TestTests.swift' (1/1)
/Users/gif/Desktop/Test/TestTests/TestTests.swift:17:5: warning: XCTest Specific Matcher Violation: Prefer the specific matcher 'XCTAssertTrue' instead. (xct_specific_matcher)
Done linting! Found 1 violation, 0 serious in 1 file.

Environment

• SwiftLint version (run swiftlint version to be sure)?
  0.43.0
• Installation method used (Homebrew, CocoaPods, building from source, etc)?
  CocoaPods
• Paste your configuration file:

only_rules:
  # Prefer specific XCTest matchers over XCTAssertEqual and XCTAssertNotEqual
  - xct_specific_matcher

• Are you using nested configurations?
  If so, paste their relative paths and respective contents.
• Which Xcode version are you using (check xcodebuild -version)?
  12.3
• Do you have a sample that shows the issue? Run echo "[string here]" | swiftlint lint --no-cache --use-stdin --enable-all-rules
  to quickly test if your example is really demonstrating the issue. If your example is more
  complex, you can use swiftlint lint --path [file here] --no-cache --enable-all-rules.

class TestTests: XCTestCase {
  var optionalBoolean: Bool? {
    return false
  }

  func testExample() throws {
    // This triggers a violation:
    XCTAssertEqual(self.optionalBoolean, true)
  }
}

Start by reproducing the reported violation with the xct_specific_matcher rule and the optional Bool example in TestTests.swift. Trace the rule's handling of XCTAssertEqual arguments and add coverage showing that an optional boolean does not trigger the violation; the lint command should then report no warning for that case.