Switch from asdf to mise (formerly called rtx) to install dependencies in .tool-versions

Overview

@pedropombeiro mentioned rtx in #dev_tip_of_the_day as an alternative to asdf that is not based on shims. rtx focuses on performance and backwards compatibility with asdf, so there wouldn't need to be any changes to the existing setup. See the benchmarks provided by @pedropombeiro below:

Another edifying benchmark:

Tasks

• Update CI jobs to use mise to test the new configuration.
• Set mise.enabled to true in the default settings.
• Ensure mise updates automatically when a new version is released.
• Update documentation to reflect the switch from asdf to mise.

Impacted categories

The following categories relate to this issue:

• gdk-reliability - e.g. When a GDK action fails to complete.
• gdk-usability - e.g. Improvements or suggestions around how the GDK functions.
• gdk-performance - e.g. When a GDK action is slow or times out.