Previously, only e2e tests were run for docs examples on CI. As a
result, unit tests (which are included in the zipped archives we provide
for users to download and play with the examples locally) were often
outdated and broken.
This commit configures specific docs examples that have meaningful unit
tests to run them on CI (via the `run-example-e2e.js` script). Where
necessary, the unit tests are fixed to ensure they pass and reflect the
changes in the corresponding component/service.
This commit also removes some auto-generated unit tests that are not
meaningful (e.g. make trivial assertions, such that a component instance
is truthy) and are often broken anyway (e.g. because the corresponding
component has been changed in ways that make the tests fail).
PR Close#36143
"app" is the default prefix for CLI projects when generating components.
This updates our examples to conform that that default
Closes#19778
PR Close#30789
`innerText` is not supported in Firefox prior to v45. In most cases (at least
the ones we are interested in), `innerText` and `textContent` work equally well,
but `textContent` is more performant (as it doesn't require a reflow).
From [MDN][1] on the differences of `innerText` vs `textContent`:
> - [...]
> - `innerText` is aware of style and will not return the text of hidden
> elements, whereas `textContent` will.
> - As `innerText` is aware of CSS styling, it will trigger a reflow, whereas
> `textContent` will not.
> - [...]
[1]: https://developer.mozilla.org/en-US/docs/Web/API/Node/textContent#Differences_from_innerTextFixes#17585
