Twig plugin: Provide a twig rewrite plugin

Sounds like a good idea! Do you need any pointers to start with writing such a plugin?

No thanks, I'll push an issue fork/MR for it in due course.

If you could add tests for it too, that would be great! (A unit test and a functional test are required in order for the code to be merged.)

Thanks for providing code and tests! Looks good at first glance.

I think that the tests fail because of the following warning:

1 test triggered 1 PHP warning:
1) /builds/issue/tamper-3530101/vendor/twig/twig/src/Template.php:345
Array to string conversion
Triggered by:
* Drupal\Tests\tamper\Unit\Plugin\Tamper\TwigTest::testTwig
/builds/issue/tamper-3530101/tests/src/Unit/Plugin/Tamper/TwigTest.php:93