Add webpack demo example

[alexeagle]

Moved from aspect-build/bazel-examples-gha#39 (that's a derived repo, all changes land here first)

[aspect-workflows]

Test

4 test targets passed

Targets

//angular/projects/my-app:test [k8-fastbuild]  6s
//angular/projects/my-lib:test [k8-fastbuild]  7s
//qwik/app:vitest [k8-fastbuild]               9s
//qwik/lib:vitest [k8-fastbuild]               12s

Total test execution time was 35s. 22 tests (84.6%) were fully cached saving 13s.

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