refactor: Move ThemeUtils and CSSBundler to internal package

[Artur-]

They are not related the the frontend build

[github-actions]

Test Results

1 307 files  ±0  1 307 suites  ±0   1h 15m 1s ⏱️ + 2m 6s
9 269 tests ±0  9 201 ✅ ±0  68 💤 ±0  0 ❌ ±0 
9 726 runs  ±0  9 650 ✅ ±0  76 💤 ±0  0 ❌ ±0 

Results for commit bb23cec. ± Comparison against base commit cb74c46.

This pull request removes 26 and adds 26 tests. Note that renamed tests count towards both.

com.vaadin.flow.server.frontend.CssBundlerTest ‑ conditionalImportsNotHandled
com.vaadin.flow.server.frontend.CssBundlerTest ‑ differentImportSyntaxesSupported
com.vaadin.flow.server.frontend.CssBundlerTest ‑ dollarAndBackslashWorks
com.vaadin.flow.server.frontend.CssBundlerTest ‑ ignoreCommentedRules
com.vaadin.flow.server.frontend.CssBundlerTest ‑ inlineImports_handlesNullNodeModulesFolder
com.vaadin.flow.server.frontend.CssBundlerTest ‑ inlineImports_prefersRelativeOverNodeModules
com.vaadin.flow.server.frontend.CssBundlerTest ‑ inlineImports_resolvesNodeModulesImport
com.vaadin.flow.server.frontend.CssBundlerTest ‑ layerImportsNotHandled
com.vaadin.flow.server.frontend.CssBundlerTest ‑ minifyCss_CSSMediaQueriesHandled
com.vaadin.flow.server.frontend.CssBundlerTest ‑ minifyCss_collapsesWhitespace
…

com.vaadin.flow.internal.CssBundlerTest ‑ conditionalImportsNotHandled
com.vaadin.flow.internal.CssBundlerTest ‑ differentImportSyntaxesSupported
com.vaadin.flow.internal.CssBundlerTest ‑ dollarAndBackslashWorks
com.vaadin.flow.internal.CssBundlerTest ‑ ignoreCommentedRules
com.vaadin.flow.internal.CssBundlerTest ‑ inlineImports_handlesNullNodeModulesFolder
com.vaadin.flow.internal.CssBundlerTest ‑ inlineImports_prefersRelativeOverNodeModules
com.vaadin.flow.internal.CssBundlerTest ‑ inlineImports_resolvesNodeModulesImport
com.vaadin.flow.internal.CssBundlerTest ‑ layerImportsNotHandled
com.vaadin.flow.internal.CssBundlerTest ‑ minifyCss_CSSMediaQueriesHandled
com.vaadin.flow.internal.CssBundlerTest ‑ minifyCss_collapsesWhitespace
…

♻️ This comment has been updated with latest results.

[sonarqubecloud]

Quality Gate passed

Issues
174 New issues
1 Accepted issue

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud