Use global isSafeURL utility

- Updated safe_link component so it uses global isSafeURL utility
- Removed obsolete code

ee/app/assets/javascripts/vue_shared/components/is_safe_url.js

-const isAbsoluteOrRootRelative = url => /^(https?:)?\//.test(url);
-
-/**
- * Checks if the provided URL is a safe URL (absolute http(s) URL)
- *
- * @param {String} url that will be checked
- * @returns {Boolean}
- */
-export default url => {
-  let parsedUrl;
-
-  if (!isAbsoluteOrRootRelative(url)) {
-    return false;
-  }
-
-  /*
-   Trying to use URL constructor, IE11 does not support it, so we fall back on the a element trick
-   */
-  try {
-    parsedUrl = new URL(url);
-  } catch (e) {
-    parsedUrl = document.createElement('a');
-    parsedUrl.href = url;
-  }
-
-  return ['http:', 'https:'].includes(parsedUrl.protocol);
-};

ee/app/assets/javascripts/vue_shared/components/safe_link.vue

 <script>
-import isSafeURL from './is_safe_url';
+import { isSafeURL } from '~/lib/utils/url_utility';
 /**
  * Renders a link element (`<a>`) if the href is a absolute http(s) URL,
  * a `<span>` element otherwise

ee/spec/frontend/vue_shared/components/is_safe_url_spec.js

-/* eslint-disable no-script-url */
-import isSafeURL from 'ee/vue_shared/components/is_safe_url';
-
-describe('isSafeUrl', () => {
-  const absoluteUrls = [
-    'http://example.org',
-    'http://example.org:8080',
-    'https://example.org',
-    'https://example.org:8080',
-    'https://192.168.1.1',
-  ];
-
-  const rootRelativeUrls = ['/relative/link'];
-
-  const relativeUrls = ['./relative/link', '../relative/link'];
-
-  const urlsWithoutHost = ['http://', 'https://', 'https:https:https:'];
-
-  const nonHttpUrls = [
-    'javascript:',
-    'javascript:alert("XSS")',
-    'jav\tascript:alert("XSS");',
-    '   javascript:alert("XSS");',
-    'ftp://192.168.1.1',
-    'file:///',
-    'file:///etc/hosts',
-  ];
-
-  const encodedJavaScriptUrls = [
-    '&#0000106&#0000097&#0000118&#0000097&#0000115&#0000099&#0000114&#0000105&#0000112&#0000116&#0000058&#0000097&#0000108&#0000101&#0000114&#0000116&#0000040&#0000039&#0000088&#0000083&#0000083&#0000039&#0000041',
-    'javascript:alert('XSS')',
-    '&#x6A&#x61&#x76&#x61&#x73&#x63&#x72&#x69&#x70&#x74&#x3A&#x61&#x6C&#x65&#x72&#x74&#x28&#x27&#x58&#x53&#x53&#x27&#x29',
-    '\\u006A\\u0061\\u0076\\u0061\\u0073\\u0063\\u0072\\u0069\\u0070\\u0074\\u003A\\u0061\\u006C\\u0065\\u0072\\u0074\\u0028\\u0027\\u0058\\u0053\\u0053\\u0027\\u0029',
-  ];
-
-  const safeUrls = [...absoluteUrls, ...rootRelativeUrls];
-  const unsafeUrls = [
-    ...relativeUrls,
-    ...urlsWithoutHost,
-    ...nonHttpUrls,
-    ...encodedJavaScriptUrls,
-  ];
-
-  describe('with URL constructor support', () => {
-    it.each(safeUrls)('returns true for %s', url => {
-      expect(isSafeURL(url)).toBe(true);
-    });
-
-    it.each(unsafeUrls)('returns false for %s', url => {
-      expect(isSafeURL(url)).toBe(false);
-    });
-  });
-
-  describe('without URL constructor support', () => {
-    beforeEach(() => {
-      jest.spyOn(window, 'URL').mockImplementation(() => {
-        throw new Error('No URL support');
-      });
-    });
-
-    it.each(safeUrls)('returns true for %s', url => {
-      expect(isSafeURL(url)).toBe(true);
-    });
-
-    it.each(unsafeUrls)('returns false for %s', url => {
-      expect(isSafeURL(url)).toBe(false);
-    });
-  });
-});