chore: remove @oclif/plugin-legacy dependency (#3659)

* chore: remove @oclif/plugin-legacy dependency

This removes the @oclif/plugin-legacy plugin which is no longer needed.

* fix: add @types/cli-progress to devDependencies

This type definition was previously provided transitively through
@oclif/plugin-legacy. Now that the legacy plugin is removed, we need
to explicitly include it as a devDependency.

* remove plugin-legacy from expected core plugins

Author: eablack