Add IfSwitchExpressionRule for enforcing if and switch statements. In…

[AballahNsour]

…clude non-triggering and triggering examples.

Add IfSwitchExpressionRule for enforcing if and switch statements. Include non-triggering and triggering examples.

[SwiftLintBot]

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⚠️	If this is a user-facing change, please include a CHANGELOG entry to credit yourself! You can find it at CHANGELOG.md.
⚠️	This PR may need tests.

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* Add IfSwitchExpressionRule for enforcing if and switch statements. In….  
  [AballahNsour](https://github.com/AballahNsour)
  [#issue_number](https://github.com/realm/SwiftLint/issues/issue_number)

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