infra: Test out mise

I found `mise` a tool to help manage development projects.
https://mise.jdx.dev/

It basically can manage ENV vars based on the directory you are in,
manages tools you need (and makes thoser available based on the
directory you are in), and allows to define simple tasks that can
then be shared between developers.

Tools can be found in npm, pipx, aqua, binaries on github, ...
and it tries to verify signatures and all that (if supported by the
repo the data comes from).

I replaces the entire autofix workflow with mise tooling and tasks,
just to give it a try :-)

To reproduce:

```sh
> cargo install mise # to get the tool itself

# Follow the necessary step
# https://mise.jdx.dev/installing-mise.html#shells
# to intergate into your shell

> cd /your/slint/folder

# Mise will now ask whether or not to trust this dir and prints the
# command needed to do so. Run that.

> mise install # Install all the tools defined in .mise/config.toml

# Add a .mise.local.toml with local overrides. Git will ignore this file.
# Or add tasks into .mise/tasks/local ... Git will also ignore those.

> mise run 'ci:autofix:**:all' # To run all the ci:autofix tasks.
```

It is so much fatser to see these checks fail locally than it is to
bother CI with them :-)

api/cpp/tests/platform_eventloop.cpp

@@ -28,7 +28,7 @@ struct TestPlatform : slint::platform::Platform
 #ifdef SLINT_FEATURE_RENDERER_SOFTWARE
         struct TestWindowAdapter : slint::platform::WindowAdapter
         {
-            slint::platform::SoftwareRenderer r { {} };
+            slint::platform::SoftwareRenderer r { { } };
             slint::PhysicalSize size() override { return slint::PhysicalSize({}); }
             slint::platform::AbstractRenderer &renderer() override { return r; }
         };