chore: use Turborepo to build

Why?

- ordering: build dependencies before dependents
- cache: don't rebuild if no changes in files or dependencies
- possibility to restrict to specific scopes

Changes:

- `yarn build` now only build `xo-server` and `xo-web` (and dependencies)
- `yarn build:xo-lite` build `@xen-orchestra/lite\ (and dependencies)

.gitignore

@@ -34,3 +34,4 @@ yarn-error.log.*
 # code coverage
 .nyc_output/
 coverage/
+.turbo/