Add typings for common-prefix (#27195)

types/common-prefix/common-prefix-tests.ts

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+import common = require('common-prefix'); // common is(string: ReadOnlyArray<string>) => string
+
+// $ExpectType string
+common(['a']);

types/common-prefix/index.d.ts

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+// Type definitions for common-prefix 1.1
+// Project: https://github.com/hughsk/common-prefix
+// Definitions by: Sean Marvi Oliver Genabe <https://github.com/seangenabe>
+// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+
+declare function common(strings: ReadonlyArray<string>): string;
+
+export = common;

types/common-prefix/tsconfig.json

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+{
+    "compilerOptions": {
+        "module": "commonjs",
+        "lib": [
+            "es5"
+        ],
+        "noImplicitAny": true,
+        "noImplicitThis": true,
+        "strictNullChecks": true,
+        "baseUrl": "../",
+        "typeRoots": [
+            "../"
+        ],
+        "types": [],
+        "noEmit": true,
+        "forceConsistentCasingInFileNames": true,
+        "strictFunctionTypes": true
+    },
+    "files": [
+        "index.d.ts",
+        "common-prefix-tests.ts"
+    ]
+}

types/common-prefix/tslint.json

@@ -0,0 +1 @@
+{ "extends": "dtslint/dt.json" }