Support schemeless funding URLs

The [GitHub documentation][1] for FUNDING.yml specifically notes that if a
custom URL is in the Array format, and includes `:` then it must be
quoted.

From this we can infer that the custom URL does not have to contain a
`:` at all.

The example for a Custom URL also gives an example of an unquoted URL
without any `:` character:

```
custom: ["https://www.paypal.me/octocat", octocat.com]
```

However if a repository uses a URL in this format it is currently
rejected because it does not specify a scheme. Furthermore the
`parse_url` method treats the `octocat.com` example as a path and not a
host. The same is true for URLs such as
`octocat.com/funding/example.html`.

This patch adds an additional allowance for the URL filter to capture
the case where a URL has no scheme or host, but does have a path.

[1]: https://docs.github.com/en/repositories/managing-your-repositorys-settings-and-features/customizing-your-repository/displaying-a-sponsor-button-in-your-repository#about-funding-files

src/Composer/Package/Loader/ValidatingArrayLoader.php

@@ -623,6 +623,14 @@ class ValidatingArrayLoader implements LoaderInterface
         }
 
         $bits = parse_url($value);
+        if ($bits === false) {
+            return false;
+        }
+
+        if (array_key_exists('path', $bits) && !array_key_exists('scheme', $bits) && !array_key_exists('host', $bits)) {
+            return true;
+        }
+
         if (empty($bits['scheme']) || empty($bits['host'])) {
             return false;
         }

tests/Composer/Test/Package/Loader/ValidatingArrayLoaderTest.php

@@ -84,6 +84,14 @@ class ValidatingArrayLoaderTest extends TestCase
                         [
                             'url' => 'https://example.org/fund',
                         ],
+                        [
+                            'type' => 'custom',
+                            'url' => 'example.com',
+                        ],
+                        [
+                            'type' => 'custom',
+                            'url' => 'example.com/fund#fundus',
+                        ],
                     ],
                     'require' => [
                         'a/b' => '1.*',

tests/Composer/Test/Repository/Vcs/GitHubDriverTest.php

@@ -166,7 +166,7 @@ class GitHubDriverTest extends TestCase
                 ['url' => $repoApiUrl, 'body' => '{"master_branch": "test_master", "owner": {"login": "composer"}, "name": "packagist"}'],
                 ['url' => 'https://api.github.com/repos/composer/packagist/contents/composer.json?ref=feature%2F3.2-foo', 'body' => '{"encoding":"base64","content":"'.base64_encode('{"support": {"source": "'.$repoUrl.'" }}').'"}'],
                 ['url' => 'https://api.github.com/repos/composer/packagist/commits/feature%2F3.2-foo', 'body' => '{"commit": {"committer":{ "date": "2012-09-10"}}}'],
-                ['url' => 'https://api.github.com/repos/composer/packagist/contents/.github/FUNDING.yml', 'body' => '{"encoding": "base64", "content": "'.base64_encode("custom: https://example.com").'"}'],
+                ['url' => 'https://api.github.com/repos/composer/packagist/contents/.github/FUNDING.yml', 'body' => '{"encoding": "base64", "content": "'.base64_encode("custom: [\"https://example.com/funding\", octocat.com]").'"}'],
             ],
             true
         );