Fix spurious "used before being assigned" errors in for of/in loops

Port of microsoft/TypeScript#61376. Adds check for isForInOrOfStatement
to prevent false positive TS2454 errors for variables declared in
for-in/for-of loops when referenced in closures within the loop body.

Co-authored-by: RyanCavanaugh <6685088+RyanCavanaugh@users.noreply.github.com>

Author: Copilot

internal/checker/checker.go

@@ -10806,9 +10806,9 @@ func (c *Checker) checkIdentifier(node *ast.Node, checkMode CheckMode) *Type {
 	// We only look for uninitialized variables in strict null checking mode, and only when we can analyze
 	// the entire control flow graph from the variable's declaration (i.e. when the flow container and
 	// declaration container are the same).
-	isNeverInitialized := immediateDeclaration != nil && ast.IsVariableDeclaration(immediateDeclaration) && immediateDeclaration.Initializer() == nil &&
-		immediateDeclaration.AsVariableDeclaration().ExclamationToken == nil && c.isMutableLocalVariableDeclaration(immediateDeclaration) &&
-		!c.isSymbolAssignedDefinitely(symbol)
+	isNeverInitialized := immediateDeclaration != nil && ast.IsVariableDeclaration(immediateDeclaration) && !ast.IsForInOrOfStatement(immediateDeclaration.Parent.Parent) &&
+		immediateDeclaration.Initializer() == nil && immediateDeclaration.AsVariableDeclaration().ExclamationToken == nil &&
+		c.isMutableLocalVariableDeclaration(immediateDeclaration) && !c.isSymbolAssignedDefinitely(symbol)
 	assumeInitialized := isParameter ||
 		isAlias ||
 		(isOuterVariable && !isNeverInitialized) ||