Grafana UI: Make it possible to bundle package with plugins (#76191)

* moved themecontext to data

* chore(grafana-ui): re-export ThemeContext from grafana/data for backwards compatibility

* Moved icon bundling to core.

* feat(plugins): share react-inlinesvg with plugins for grafana/ui bundling

* chore(codeowners): add generate-icon-bundle.js to file

* chore(storybook): update path to iconBundle file for theme

* feat(plugins): share i18n dependency via systemjs

* Make sure that icon bundle is initialized for tests.

* Removed comment.

* added tests for icon root.

* Removing the need of having an init variable.

* feat(grafana-ui): add icon svgs to bundle for projects that don't rely on grafana

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Co-authored-by: Marcus Andersson <marcus.andersson@grafana.com>

.github/CODEOWNERS

@@ -506,6 +506,7 @@ cypress.config.js @grafana/grafana-frontend-platform
 /scripts/trigger_windows_build.sh @grafana/grafana-delivery
 /scripts/cleanup-husky.sh @grafana/frontend-ops
 /scripts/verify-repo-update/ @grafana/grafana-delivery
+scripts/generate-icon-bundle.js @grafana/plugins-platform-frontend @grafana/grafana-frontend-platform
 
 /scripts/webpack/ @grafana/frontend-ops
 /scripts/generate-a11y-report.sh @grafana/grafana-frontend-platform