PHPUnit 10 Migration (#1302)

* Bump PHPUnit dependencies

* Set return type of base TestCase methods

From the [PHPUnit 8 release notes][1], the `TestCase` methods below now declare a `void` return type:

- `setUpBeforeClass()`
- `setUp()`
- `assertPreConditions()`
- `assertPostConditions()`
- `tearDown()`
- `tearDownAfterClass()`
- `onNotSuccessfulTest()`

[1]: https://phpunit.de/announcements/phpunit-8.html

* Ignore PHPUnit cache folder

* Adopt PHP attributes in test classes

* Declare data providers as `static`

* Add return types to test methods

* Define test classes as `final`

* Migrate phpunit.xml to phpunit 10

* Correct phpunit attribute class name

* Rename base test class

* Restructure test folders

* Fix test image paths

* Only set rules for php files in .editorconfig

* Remove php unit flag in local test env

---------

Co-authored-by: Shift <shift@laravelshift.com>

tests/Unit/OriginTest.php

@@ -0,0 +1,39 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Intervention\Image\Tests\Unit;
+
+use Intervention\Image\Origin;
+use Intervention\Image\Tests\BaseTestCase;
+
+final class OriginTest extends BaseTestCase
+{
+    public function testFilePath(): void
+    {
+        $origin = new Origin('image/jpeg', $this->getTestImagePath('example.jpg'));
+        $this->assertEquals($this->getTestImagePath('example.jpg'), $origin->filePath());
+    }
+
+    public function testFileExtension(): void
+    {
+        $origin = new Origin('image/jpeg', $this->getTestImagePath('example.jpg'));
+        $this->assertEquals('jpg', $origin->fileExtension());
+
+        $origin = new Origin('image/jpeg');
+        $this->assertEquals('', $origin->fileExtension());
+    }
+
+    public function testSetGetMediaType(): void
+    {
+        $origin = new Origin();
+        $this->assertEquals('application/octet-stream', $origin->mediaType());
+
+        $origin = new Origin('image/gif');
+        $this->assertEquals('image/gif', $origin->mediaType());
+        $this->assertEquals('image/gif', $origin->mimetype());
+        $result = $origin->setMediaType('image/jpeg');
+        $this->assertEquals('image/jpeg', $origin->mediaType());
+        $this->assertEquals('image/jpeg', $result->mediaType());
+    }
+}