* refactor(frontend): rename all @grafana/data/src imports to @grafana/data
* feat(grafana-data): introduce internal entrypoint for sharing code only with grafana
* feat(grafana-data): add test entrypoint for data test utils usage in core
* refactor(frontend): update import paths to use grafana/data exports entrypoints
* docs(grafana-data): update comment in internal/index.ts
* refactor(frontend): prefer public namespaced exports over re-exporting via internal
* chore(frontend): fix a couple more weird paths that typescript complains about
* refactor(frontend): rename all @grafana/data/src imports to @grafana/data
* feat(grafana-data): introduce internal entrypoint for sharing code only with grafana
* feat(grafana-data): add test entrypoint for data test utils usage in core
* refactor(frontend): update import paths to use grafana/data exports entrypoints
* docs(grafana-data): update comment in internal/index.ts
* refactor(frontend): prefer public namespaced exports over re-exporting via internal