This PR updates the Rust toolchain to recent nightly.
Most of the changes are related to fixing newly added warnings and adjusting the feature flags. Also the formatter changed its behavior slightly, causing some whitespace changes.
Other points:
* Changed debug level of the `buildscript` profile to `lint-tables-only` — this should improve the build times and space usage somewhat.
* Moved lint configuration to the worksppace `Cargo.toml` definition. Adjusted the formatter appropriately.
* Removed auto-generated IntelliJ run configurations, as they are not useful anymore.
* Added a few trivial stdlib nightly functions that were removed to our codebase.
* Bumped many dependencies but still not all:
* `clap` bump encountered https://github.com/clap-rs/clap/issues/5407 — for now the warnings were silenced by the lint config.
* `octocrab` — our forked diverged to far with the original, needs more refactoring.
* `derivative` — is unmaintained and has no updated version, despite introducing warnings in the generated code. There is no direct replacement.
Removes the old GUI1 code base and reduces the Rust code footprint by removing unused code.
# Important Notes
Updates build scripts and reformats part of the codebase with the autoformatter.
