Fix module id conflict on a case insensitive OS

Suppose we have to files named `date.js` and `Date.js`, `makeUnique`
treats these two files are different currently. But on a case
insensitive OS, they are the same file. The commit try to fix the
problem.

src/utils/renderNamePattern.ts

@@ -31,12 +31,15 @@ export function renderNamePattern(
 }
 
 export function makeUnique(name: string, existingNames: Record<string, any>) {
-	if (name in existingNames === false) return name;
-
-	const ext = extname(name);
-	name = name.substr(0, name.length - ext.length);
-	let uniqueName,
-		uniqueIndex = 1;
-	while (existingNames[(uniqueName = name + ++uniqueIndex + ext)]);
-	return uniqueName;
+	for (const existingName of Object.keys(existingNames)) {
+		if (name.toLowerCase() === existingName.toLowerCase()) {
+			const ext = extname(name);
+			name = name.substr(0, name.length - ext.length);
+			let uniqueName,
+				uniqueIndex = 1;
+			while (existingNames[(uniqueName = name + ++uniqueIndex + ext)]);
+			return uniqueName;
+		}
+	}
+	return name;
 }