- Remove the Kubernetes official plugin.
- `hello` and `language-toy` move from `plugins/` to
`crates/ide-plugin/tests/fixtures/`: they stay what the host's tests run
against, but are no longer listed as plugins of the repository.
- A `jobs` fixture takes over what only Kubernetes exercised: a tree view
filled by a pinned program, a terminal for the activated entry in the
invoking window, string and number settings, locally and in remote
projects.
- `plugins/` now holds only the official plugins; `build.sh`, CI and the
debug plugin catalog follow.
