Use weighted algorithm for string matching when finding files in repo (#21370)

This PR is for:
* https://github.com/go-gitea/gitea/issues/20231

Now, when a user searches `word`, they always see `/{word}.txt` before
`/{w}e-g{o}t-{r}esult.{d}at`

Demo:

When searching "a", "a.ext" comes first. 

Then when searching "at", the longer matched "template" comes first.

<details>


![image](https://user-images.githubusercontent.com/2114189/194588738-3644d891-956f-40e4-b79b-b97d34265456.png)


![image](https://user-images.githubusercontent.com/2114189/194588797-9b124670-4e1e-4510-a170-780295ed89b8.png)

</details>

This PR also makes the frontend tests could import feature JS files by
introducing `jestSetup.js`

Co-authored-by: delvh <dev.lh@web.de>
Co-authored-by: silverwind <me@silverwind.io>

jest.config.js

@@ -1,3 +1,4 @@
+// to run tests with ES6 module, node must run with "--experimental-vm-modules", or see Makefile's "test-frontend" for reference
 export default {
   rootDir: 'web_src',
   setupFilesAfterEnv: ['jest-extended/all'],
@@ -7,6 +8,8 @@ export default {
   transform: {
     '\\.svg$': '<rootDir>/js/testUtils/jestRawLoader.js',
   },
+  setupFiles: [
+    './js/testUtils/jestSetup.js', // prepare global variables used by our code (eg: window.config)
+  ],
   verbose: false,
 };
-