Previously, the examples in the `comparing-observables` guide were hard-coded.
This made it impossible to test them and verify they are correct.
This commit fixes this by converting them into a proper mini-app. In a
subsequent commit, tests will be added to verify that the source code
works as expected (and guard against regressions).
Fixes#31024
PR Close#34327
Sonu Kapoor
thanhpd
Suguru Inatomi
thanhpd
Ro Savage
Anuj
SangKa.Z
Jason Aden