Create rule S7430: splitn should not be used with a limit of 0 or 1 (#4771)

* Create rule S7430

* Update RSPEC

---------

Co-authored-by: yassin-kammoun-sonarsource <yassin-kammoun-sonarsource@users.noreply.github.com>
Co-authored-by: yassin-kammoun-sonarsource <yassin.kammoun@sonarsource.com>

rules/S7430/metadata.json

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+{
+}

rules/S7430/rust/metadata.json

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+{
+  "title": "`splitn` should not be used with a limit of 0 or 1",
+  "type": "BUG",
+  "status": "ready",
+  "remediation": {
+    "func": "Constant\/Issue",
+    "constantCost": "5min"
+  },
+  "tags": [
+    "clippy"
+  ],
+  "defaultSeverity": "Major",
+  "ruleSpecification": "RSPEC-7430",
+  "sqKey": "S7430",
+  "scope": "All",
+  "defaultQualityProfiles": ["Sonar way"],
+  "quickfix": "unknown",
+  "code": {
+    "impacts": {
+      "RELIABILITY": "MEDIUM"
+    },
+    "attribute": "LOGICAL"
+  }
+}

rules/S7430/rust/rule.adoc

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+== Why is this an issue?
+
+When using `splitn` with zero or one splits, the function does not actually split the value, which is likely not the intended behavior.
+
+=== Code examples
+
+==== Noncompliant code example
+
+[source,rust,diff-id=1,diff-type=noncompliant]
+----
+let s = "";
+for x in s.splitn(1, ":") { // Noncompliant
+    // ..
+}
+----
+
+==== Compliant solution
+
+[source,rust,diff-id=1,diff-type=compliant]
+----
+let s = "";
+for x in s.splitn(2, ":") { // Compliant
+    // ..
+}
+----
+
+== Resources
+=== Documentation
+
+* Clippy Lints - https://rust-lang.github.io/rust-clippy/master/index.html#suspicious_splitn