feature: new rules identical-switch-branches and identical-ifelseif-branches

These new rules result from the refactoring of `identical-branches` that will cover only simple/single if..else statements.

testdata/identical_ifelseif_branches.go

@@ -0,0 +1,80 @@
+package fixtures
+
+func identicalIfElseIfBranches() {
+
+	if true { // MATCH /"if...else if" chain with identical branches (lines 5 and 13)/
+		print("something")
+	} else if true {
+		print("something else")
+	} else if true {
+		print("other thing")
+	} else if false {
+		println()
+	} else {
+		print("something")
+	}
+
+	if true { // MATCH /"if...else if" chain with identical branches (lines 17 and 23)/
+		print("something")
+	} else if true {
+		print("something else")
+	} else if true {
+		print("other thing")
+	} else if false {
+		print("something")
+	} else {
+		println()
+	}
+
+	if true {
+		print("something")
+	} else if true {
+		print("something else")
+		if true { // MATCH /"if...else if" chain with identical branches (lines 33 and 35)/
+			print("something")
+		} else if false {
+			print("something")
+		} else {
+			println()
+		}
+	}
+
+	// Should not warn because even if branches are identical, the err variable is not
+	if err := something(); err != nil {
+		println(err)
+	} else if err := somethingElse(); err != nil {
+		println(err)
+	}
+
+	// Multiple identical pair of branches
+	if a {
+		foo()
+	} else if b {
+		bar()
+	} else if c {
+		foo()
+	} else if d {
+		bar()
+	}
+	// MATCH:50 /"if...else if" chain with identical branches (lines 50 and 54)/
+	// MATCH:50 /"if...else if" chain with identical branches (lines 52 and 56)/
+
+	if createFile() { // json:{"MATCH": "\"if...else if\" chain with identical branches (lines 62 and 66)","Confidence": 0.8}
+		doSomething()
+	} else if !delete() {
+		return new("cannot delete file")
+	} else if createFile() {
+		doSomething()
+	} else {
+		return new("file error")
+	}
+
+	// Test confidence is reset
+	if a { // json:{"MATCH": "\"if...else if\" chain with identical branches (lines 73 and 75)","Confidence": 1}
+		foo()
+	} else if b {
+		foo()
+	} else {
+		bar()
+	}
+}